Solve the following quadratic equations by factorization method ( 1 – 9).

Question 1: x^2 +1  = 0 

Answer:

x^2 +1  = 0 

\Rightarrow x^2 - i^2  = 0 

\Rightarrow (x-i)(x+i) = 0 

\Rightarrow x = i \text{ or } x = -i   

Hence the root of the equation x^2 +1  = 0  are i \ \text{ and } \ (-i)

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Question 2: 9x^2 + 4 = 0  

Answer:

9x^2 + 4 = 0  

\Rightarrow (3x)^2 - (2i)^2  = 0 

\Rightarrow (3x-2i)(3x+2i) = 0 

\Rightarrow x = \frac{2i}{3} \text{ or } x = -\frac{2i}{3}  

Hence the root of the equation 9x^2 + 4 = 0   are \frac{2i}{3} \ \text{ and } \ -\frac{2i}{3}

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Question 3: x^2 + 2x + 5 = 0  

Answer:

x^2 + 2x + 5 = 0  

x^2 + 2x + 1+4 = 0  

\Rightarrow (x+1)^2 - (2i)^2 = 0 

\Rightarrow (x+1-2i)(x+1+2i) = 0 

\Rightarrow x = (-1+2i) \text{ or } x = (-1-2i)   

Hence the root of the equation x^2 + 2x + 5 = 0   are (-1+2i) \ \text{ and } \ (-1-2i)

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Question 4: 4x^2 - 12 x + 25 = 0  

Answer:

4x^2 - 12 x + 25 = 0  

4x^2 - 12 x + 9 + 16 = 0  

\Rightarrow (2x-3)^2 - (4i)^2 = 0 

\Rightarrow (2x-3-4i)(2x-3+4i) = 0 

\Rightarrow x = \frac{3+4i}{2} \text{ or } x = \frac{3-4i}{2}   

\Rightarrow x = (\frac{3}{2}+ 2i) \text{ or } x = (\frac{3}{2} - 2i)   

Hence the root of the equation 4x^2 - 12 x + 25 = 0   are (\frac{3}{2}+ 2i) \ \text{ and } \ (\frac{3}{2} - 2i)

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Question 5: x^2 + x + 1 = 0 

Answer:

x^2 + x + 1 = 0  

x^2 + x + \frac{1}{4} + \frac{3}{4} = 0  

\Rightarrow (x+ \frac{1}{2})^2 - (\frac{\sqrt{3}}{2}i)^2 = 0 

\Rightarrow (x+ \frac{1}{2} - \frac{\sqrt{3}}{2}i )(x+ \frac{1}{2} + \frac{\sqrt{3}}{2}i ) = 0 

\Rightarrow x = (-\frac{1}{2}+ \frac{\sqrt{3}}{2}i) \text{ or } x = (-\frac{1}{2}- \frac{\sqrt{3}}{2}i)   

Hence the root of the equation x^2 + x + 1 = 0  are (-\frac{1}{2}+ \frac{\sqrt{3}}{2}i) \ \text{ and } \ (-\frac{1}{2}- \frac{\sqrt{3}}{2}i)

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Question 6: 4x^2 + 1 = 0

Answer:

4x^2 + 1 = 0

\Rightarrow (2x)^2 - i^2  = 0 

\Rightarrow (2x-i)(2x+i) = 0 

\Rightarrow x = \frac{i}{2} \text{ or } x = \frac{-i}{2}   

Hence the root of the equation 4x^2 + 1 = 0 are \frac{i}{2} \ \text{ and } \ \frac{-i}{2}

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Question 7: x^2 - 4x + 7 = 0 

Answer:

x^2 - 4x + 7 = 0 

\Rightarrow x^2 - 4x + 4 + 3 = 0 

\Rightarrow (x-2)^2 - (\sqrt{3}i)^2 = 0 

\Rightarrow (x-2-\sqrt{3} i)(x-2+\sqrt{3}i) = 0 

\Rightarrow x = (2+\sqrt{3} i) \text{ or } x = (2 - \sqrt{3} i)   

Hence the root of the equation x^2 - 4x + 7 = 0  are (2+\sqrt{3} i) \ \text{ and } \ (2 - \sqrt{3} i)

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Question 8: x^2 + 2x + 2 = 0

Answer:

x^2 + 2x + 2 = 0

\Rightarrow x^2 + 2x + 1+1 = 0

\Rightarrow (x+1)^2 - (i)^2 = 0 

\Rightarrow (x+1-i)(x+1+i) = 0 

\Rightarrow x = (-1+i) \text{ or } x = (-1-i)   

Hence the root of the equation x^2 + 2x + 2 = 0 are (-1+i) \ \text{ and } \ (-1-i)

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Question 9: 5x^2 - 6x+2 = 0

Answer:

5x^2 - 6x+2 = 0

Comparing the given equation with general form of quadratic equation ax^2 + bx + c = 0 we get,

\Rightarrow a = 5,  \ b= -6  \text{ and } c = 2

Substituting these values in

\alpha = \frac{-b + \sqrt{b^2 - 4ac} }{2a}   and  \beta = \frac{-b - \sqrt{b^2 - 4ac} }{2a}

\Rightarrow \alpha = \frac{6 + \sqrt{36 - 4 \times 5 \times 2} }{2 \times 5}   and  \beta = \frac{6 - \sqrt{36 - 4 \times 5 \times 2} }{2 \times 5}

\Rightarrow \alpha = \frac{6 + \sqrt{-4} }{10}   and  \beta = \frac{6 - \sqrt{-4} }{10}

\Rightarrow \alpha = \frac{6 + 2i }{10}   and  \beta = \frac{6 - 2i }{10}

\Rightarrow \alpha = \frac{3}{5} + \frac{1}{5} i   and  \beta = \frac{3}{5} + \frac{1}{5} i

Hence the roots of the equation are \frac{3}{5} \pm \frac{1}{5} i

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Solve the following quadratics:

Question 10: 21x^2 + 9x + 1 = 0

Answer:

21x^2 + 9x + 1 = 0

Comparing the given equation with general form of quadratic equation ax^2 + bx + c = 0 we get,

\Rightarrow a = 21,  \ b= 9  \text{ and } c = 1

Substituting these values in

\alpha = \frac{-b + \sqrt{b^2 - 4ac} }{2a}   and  \beta = \frac{-b - \sqrt{b^2 - 4ac} }{2a}

\Rightarrow \alpha = \frac{-9 + \sqrt{81 - 4 \times 21 \times 1} }{2 \times 21}   and  \beta = \frac{-9 - \sqrt{81 - 4 \times 21 \times 1} }{2 \times 21}

\Rightarrow \alpha = \frac{-9 + \sqrt{-3} }{42}   and  \beta = \frac{-9 - \sqrt{-3} }{42}

\Rightarrow \alpha = \frac{-9 + \sqrt{3}i }{42}   and  \beta = \frac{-9 - \sqrt{3}i }{42}

\Rightarrow \alpha = \frac{-3}{14} + \frac{\sqrt{3}}{42} i   and  \beta = \frac{-3}{14} - \frac{\sqrt{3}}{42} i

Hence the roots of the equation are \frac{-3}{14} \pm \frac{\sqrt{3}}{42} i

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Question 11: x^2 - x + 1=0

Answer:

x^2 - x + 1=0

Comparing the given equation with general form of quadratic equation ax^2 + bx + c = 0 we get,

\Rightarrow a = 1,  \ b= -1  \text{ and } c = 1

Substituting these values in

\alpha = \frac{-b + \sqrt{b^2 - 4ac} }{2a}   and  \beta = \frac{-b - \sqrt{b^2 - 4ac} }{2a}

\Rightarrow \alpha = \frac{1 + \sqrt{1 - 4 \times 1 \times 1} }{2 \times 1}   and  \beta = \frac{1 - \sqrt{1 - 4 \times 1 \times 1} }{2 \times 1}

\Rightarrow \alpha = \frac{1 + \sqrt{-3} }{2}   and  \beta = \frac{1 - \sqrt{-3} }{2}

\Rightarrow \alpha = \frac{1 + \sqrt{3}i }{2}   and  \beta = \frac{1 - \sqrt{3}i }{2}

\Rightarrow \alpha = \frac{1}{2} + \frac{\sqrt{3}}{2} i   and  \beta = \frac{1}{2} - \frac{\sqrt{3}}{2} i

Hence the roots of the equation are \frac{1}{2} \pm \frac{\sqrt{3}}{2} i

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Question 12: x^2 + x + 1=0

Answer:

x^2 + x + 1=0

Comparing the given equation with general form of quadratic equation ax^2 + bx + c = 0 we get,

\Rightarrow a = 1,  \ b= 1  \text{ and } c = 1

Substituting these values in

\alpha = \frac{-b + \sqrt{b^2 - 4ac} }{2a}   and  \beta = \frac{-b - \sqrt{b^2 - 4ac} }{2a}

\Rightarrow \alpha = \frac{-1 + \sqrt{1 - 4 \times 1 \times 1} }{2 \times 1}   and  \beta = \frac{-1 - \sqrt{1 - 4 \times 1 \times 1} }{2 \times 1}

\Rightarrow \alpha = \frac{-1 + \sqrt{-3} }{2}   and  \beta = \frac{-1 - \sqrt{-3} }{2}

\Rightarrow \alpha = \frac{-1 + \sqrt{3}i }{2}   and  \beta = \frac{-1 - \sqrt{3}i }{2}

\Rightarrow \alpha = \frac{-1}{2} + \frac{\sqrt{3}}{2} i   and  \beta = \frac{-1}{2} - \frac{\sqrt{3}}{2} i

Hence the roots of the equation are \frac{-1}{2} \pm \frac{\sqrt{3}}{2} i

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Question 13: 17x^2 -8x + 1 = 0

Answer:

17x^2 -8x + 1 = 0

Comparing the given equation with general form of quadratic equation ax^2 + bx + c = 0 we get,

\Rightarrow a = 17,  \ b= -8  \text{ and } c = 1

Substituting these values in

\alpha = \frac{-b + \sqrt{b^2 - 4ac} }{2a}   and  \beta = \frac{-b - \sqrt{b^2 - 4ac} }{2a}

\Rightarrow \alpha = \frac{8 + \sqrt{64 - 4 \times 17 \times 1} }{2 \times 17}   and  \beta = \frac{8 - \sqrt{64 - 4 \times 17 \times 1} }{2 \times 17}

\Rightarrow \alpha = \frac{8 + \sqrt{-4} }{34}   and  \beta = \frac{8 - \sqrt{-4} }{34}

\Rightarrow \alpha = \frac{8 + 2i }{34}   and  \beta = \frac{8-2i }{34}

\Rightarrow \alpha = \frac{4}{17} + \frac{1}{17} i   and  \beta = \frac{4}{17} - \frac{1}{17} i

Hence the roots of the equation are \frac{4}{17} \pm \frac{1}{17} i

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Question 14: 27x^2-10x + 1=0

Answer:

27x^2-10x + 1=0

Comparing the given equation with general form of quadratic equation ax^2 + bx + c = 0 we get,

\Rightarrow a = 27,  \ b= -10  \text{ and } c = 1

Substituting these values in

\alpha = \frac{-b + \sqrt{b^2 - 4ac} }{2a}   and  \beta = \frac{-b - \sqrt{b^2 - 4ac} }{2a}

\Rightarrow \alpha = \frac{10 + \sqrt{100 - 4 \times 27 \times 1} }{2 \times 27}   and  \beta = \frac{10 - \sqrt{100 - 4 \times 27 \times 1} }{2 \times 27}

\Rightarrow \alpha = \frac{10 + \sqrt{-8} }{54}   and  \beta = \frac{10 - \sqrt{-8} }{54}

\Rightarrow \alpha = \frac{10 + 2\sqrt{2}i }{54}   and  \beta = \frac{10-2\sqrt{2}i }{54}

\Rightarrow \alpha = \frac{5}{27} + \frac{\sqrt{2}}{27} i   and  \beta = \frac{5}{27} - \frac{\sqrt{2}}{17} i

Hence the roots of the equation are \frac{5}{27} \pm \frac{\sqrt{2}}{27} i

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Question 15: 17x^2 + 28x + 12 = 0

Answer:

17x^2 + 28x + 12 = 0

Comparing the given equation with general form of quadratic equation ax^2 + bx + c = 0 we get,

\Rightarrow a = 17,  \ b= 28  \text{ and } c = 12

Substituting these values in

\alpha = \frac{-b + \sqrt{b^2 - 4ac} }{2a}   and  \beta = \frac{-b - \sqrt{b^2 - 4ac} }{2a}

\Rightarrow \alpha = \frac{-28 + \sqrt{784 - 4 \times 17 \times 12} }{2 \times 17}   and  \beta = \frac{-28 - \sqrt{784 - 4 \times 17 \times 12} }{2 \times 17}

\Rightarrow \alpha = \frac{-28 + \sqrt{-32} }{34}   and  \beta = \frac{-28 - \sqrt{-32} }{34}

\Rightarrow \alpha = \frac{-28 + 4\sqrt{2} i }{34}   and  \beta = \frac{-28 - 4\sqrt{2} i }{34}

\Rightarrow \alpha = \frac{-14}{17} + \frac{2\sqrt{2}}{17} i   and  \beta = \frac{-14}{17} - \frac{2\sqrt{2}}{17} i

Hence the roots of the equation are \frac{-14}{17} \pm \frac{2\sqrt{2}}{17} i

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Question 16: 21x^2-28x+10=0

Answer:

21x^2-28x+10=0

Comparing the given equation with general form of quadratic equation ax^2 + bx + c = 0 we get,

\Rightarrow a = 21,  \ b= -28  \text{ and } c = 10

Substituting these values in

\alpha = \frac{-b + \sqrt{b^2 - 4ac} }{2a}   and  \beta = \frac{-b - \sqrt{b^2 - 4ac} }{2a}

\Rightarrow \alpha = \frac{28 + \sqrt{784 - 4 \times 21 \times 10} }{2 \times 21}   and  \beta = \frac{28 - \sqrt{784 - 4 \times 21 \times 10} }{2 \times 21}

\Rightarrow \alpha = \frac{28 + \sqrt{-56} }{42}   and  \beta = \frac{28 - \sqrt{-56} }{42}

\Rightarrow \alpha = \frac{28 + 2\sqrt{14} i }{42}   and  \beta = \frac{28 - 2\sqrt{14} i }{42}

\Rightarrow \alpha = \frac{2}{3} + \frac{\sqrt{14}}{21} i   and  \beta = \frac{2}{3} - \frac{\sqrt{14}}{21} i

Hence the roots of the equation are \frac{2}{3} \pm \frac{\sqrt{14}}{21} i

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Question 17: 8x^2-9x+3=0

Answer:

8x^2-9x+3=0

Comparing the given equation with general form of quadratic equation ax^2 + bx + c = 0 we get,

\Rightarrow a = 8,  \ b= -9  \text{ and } c = 3

Substituting these values in

\alpha = \frac{-b + \sqrt{b^2 - 4ac} }{2a}   and  \beta = \frac{-b - \sqrt{b^2 - 4ac} }{2a}

\Rightarrow \alpha = \frac{9 + \sqrt{81 - 4 \times 8 \times 3} }{2 \times 8}   and  \beta = \frac{9 - \sqrt{81 - 4 \times 8 \times 3} }{2 \times 8}

\Rightarrow \alpha = \frac{9 + \sqrt{-15} }{16}   and  \beta = \frac{9 - \sqrt{-15} }{16}

\Rightarrow \alpha = \frac{9 + \sqrt{15} i }{16}   and  \beta = \frac{9 - \sqrt{15} i }{16}

\Rightarrow \alpha = \frac{9}{16} + \frac{\sqrt{15}}{16} i   and  \beta = \frac{9}{16} - \frac{\sqrt{15}}{16} i

Hence the roots of the equation are \frac{9}{16} \pm \frac{\sqrt{15}}{16} i

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Question 18: 13x^2+7x+1=0

Answer:

13x^2+7x+1=0

Comparing the given equation with general form of quadratic equation ax^2 + bx + c = 0 we get,

\Rightarrow a = 13,  \ b= 7  \text{ and } c = 1

Substituting these values in

\alpha = \frac{-b + \sqrt{b^2 - 4ac} }{2a}   and  \beta = \frac{-b - \sqrt{b^2 - 4ac} }{2a}

\Rightarrow \alpha = \frac{-7 + \sqrt{49 - 4 \times 13 \times 1} }{2 \times 13}   and  \beta = \frac{-7 - \sqrt{49 - 4 \times 13 \times 1} }{2 \times 13}

\Rightarrow \alpha = \frac{-7 + \sqrt{-3} }{26}   and  \beta = \frac{-7 - \sqrt{-3} }{26}

\Rightarrow \alpha = \frac{-7 + \sqrt{3} i }{26}   and  \beta = \frac{-7 - \sqrt{3} i }{26}

\Rightarrow \alpha = \frac{-7}{26} + \frac{\sqrt{3}}{26} i   and  \beta = \frac{-7}{26} - \frac{\sqrt{3}}{26} i

Hence the roots of the equation are \frac{-7}{26} \pm \frac{\sqrt{3}}{26} i

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Question 19: 2x^2+x+1=0

Answer:

2x^2+x+1=0

Comparing the given equation with general form of quadratic equation ax^2 + bx + c = 0 we get,

\Rightarrow a = 2,  \ b= 1  \text{ and } c = 1

Substituting these values in

\alpha = \frac{-b + \sqrt{b^2 - 4ac} }{2a}   and  \beta = \frac{-b - \sqrt{b^2 - 4ac} }{2a}

\Rightarrow \alpha = \frac{-1 + \sqrt{1 - 4 \times 2 \times 1} }{2 \times 2}   and  \beta = \frac{-1 - \sqrt{1 - 4 \times 2 \times 1} }{2 \times 2}

\Rightarrow \alpha = \frac{-1 + \sqrt{-7} }{4}   and  \beta = \frac{-1 - \sqrt{-7} }{4}

\Rightarrow \alpha = \frac{-1 + \sqrt{7} i }{4}   and  \beta = \frac{-1 - \sqrt{7} i }{4}

\Rightarrow \alpha = \frac{-1}{4} + \frac{\sqrt{7}}{4} i   and  \beta = \frac{-1}{4} - \frac{\sqrt{7}}{4} i

Hence the roots of the equation are \frac{-1}{4} \pm \frac{\sqrt{7}}{4} i

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Question 20: \sqrt{3} x^2 -\sqrt{2} x + 3 \sqrt{3} = 0

Answer:

\sqrt{3} x^2 -\sqrt{2} x + 3 \sqrt{3} = 0

Comparing the given equation with general form of quadratic equation ax^2 + bx + c = 0 we get,

\Rightarrow a = \sqrt{3},  \ b= -\sqrt{2}  \text{ and } c = 3\sqrt{3}

Substituting these values in

\alpha = \frac{-b + \sqrt{b^2 - 4ac} }{2a}   and  \beta = \frac{-b - \sqrt{b^2 - 4ac} }{2a}

\Rightarrow \alpha = \frac{\sqrt{2} + \sqrt{2 - 4 \times \sqrt{3} \times 3\sqrt{3}} }{2 \times \sqrt{3}}   and  \beta = \frac{\sqrt{2} - \sqrt{2 - 4 \times \sqrt{3} \times 3\sqrt{3}} }{2 \times \sqrt{3}}

\Rightarrow \alpha = \frac{\sqrt{2} + \sqrt{-34} }{2\sqrt{3}}   and  \beta = \frac{\sqrt{2} - \sqrt{-34} }{2\sqrt{3}}

\Rightarrow \alpha = \frac{\sqrt{2} + \sqrt{34} i }{2\sqrt{3}}   and  \beta = \frac{\sqrt{2} - \sqrt{34} i }{2\sqrt{3}}

\Rightarrow \alpha = \frac{1}{\sqrt{6}} + \frac{\sqrt{17}}{\sqrt{6}} i   and  \beta = \frac{1}{\sqrt{6}} - \frac{\sqrt{17}}{\sqrt{6}} i

Hence the roots of the equation are \frac{1}{\sqrt{6}} \pm \frac{\sqrt{17}}{\sqrt{6}} i

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Question 21: \sqrt{2} x^2 + x + \sqrt{2} = 0

Answer:

\sqrt{2} x^2 + x + \sqrt{2} = 0

Comparing the given equation with general form of quadratic equation ax^2 + bx + c = 0 we get,

\Rightarrow a = \sqrt{2},  \ b= 1  \text{ and } c = \sqrt{2}

Substituting these values in

\alpha = \frac{-b + \sqrt{b^2 - 4ac} }{2a}   and  \beta = \frac{-b - \sqrt{b^2 - 4ac} }{2a}

\Rightarrow \alpha = \frac{-1 + \sqrt{1 - 4 \times \sqrt{2} \times \sqrt{2}} }{2 \times \sqrt{2}}   and  \beta = \frac{-1 - \sqrt{1 - 4 \times \sqrt{2} \times \sqrt{2}} }{2 \times \sqrt{2}}

\Rightarrow \alpha = \frac{-1 + \sqrt{-7} }{2\sqrt{2}}   and  \beta = \frac{-1 - \sqrt{-7} }{2\sqrt{2}}

\Rightarrow \alpha = \frac{-1 + \sqrt{7} i }{2\sqrt{2}}   and  \beta = \frac{-1 - \sqrt{7} i }{2\sqrt{2}}

\Rightarrow \alpha = \frac{-1}{2\sqrt{2}} + \frac{\sqrt{7}}{2\sqrt{2}} i   and  \beta = \frac{-1}{2\sqrt{2}} - \frac{\sqrt{7}}{2\sqrt{2}} i

Hence the roots of the equation are \frac{-1}{2\sqrt{2}} \pm \frac{\sqrt{7}}{2\sqrt{2}} i

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Question 22: x^2 + x + \frac{1}{\sqrt{2}} = 0

Answer:

x^2 + x + \frac{1}{\sqrt{2}} = 0

Comparing the given equation with general form of quadratic equation ax^2 + bx + c = 0 we get,

\Rightarrow a = 1,  \ b= 1  \text{ and } c = \frac{1}{\sqrt{2}}

Substituting these values in

\alpha = \frac{-b + \sqrt{b^2 - 4ac} }{2a}   and  \beta = \frac{-b - \sqrt{b^2 - 4ac} }{2a}

\Rightarrow \alpha = \frac{-1 + \sqrt{1 - 4 \times 1 \times \frac{1}{\sqrt{2}} }}{2 \times 1}   and  \beta = \frac{-1 - \sqrt{ 1 - 4 \times 1 \times \frac{1}{\sqrt{2} } }}{2 \times 1}

\Rightarrow \alpha = \frac{-1 - 2\sqrt{2} }{2}   and  \beta = \frac{-1 - 2\sqrt{2} }{2}

\Rightarrow \alpha = \frac{-1 + \sqrt{2\sqrt{2} -1} i }{2}   and  \beta = \frac{-1 - \sqrt{2\sqrt{2} -1} i }{2}

Hence the roots of the equation are \frac{-1 \pm \sqrt{2\sqrt{2} -1} i }{2}  

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Question 23: x^2 + \frac{x}{\sqrt{2}} + 1 = 0

Answer:

x^2 + \frac{x}{\sqrt{2}} + 1 = 0

Comparing the given equation with general form of quadratic equation ax^2 + bx + c = 0 we get,

\Rightarrow a = 1,  \ b= \frac{1}{\sqrt{2}}  \text{ and } c = 1

Substituting these values in

\alpha = \frac{-b + \sqrt{b^2 - 4ac} }{2a}   and  \beta = \frac{-b - \sqrt{b^2 - 4ac} }{2a}

\Rightarrow \alpha = \frac{-\frac{1}{\sqrt{2}} + \sqrt{\frac{1}{2} - 4 \times 1 \times 1} }{2 \times 1}   and  \beta = \frac{-\frac{1}{\sqrt{2}} - \sqrt{\frac{1}{2} - 4 \times 1 \times 1} }{2 \times 1}

\Rightarrow \alpha = \frac{-\frac{1}{\sqrt{2}} + \sqrt{\frac{-7}{2}} }{2}   and  \beta = \frac{-\frac{1}{\sqrt{2}} - \sqrt{\frac{-7}{2}} }{2}

\Rightarrow \alpha = \frac{-1 + i\sqrt{7}  }{2\sqrt{2}}   and  \beta = \frac{-1 - i\sqrt{7}  }{2\sqrt{2}}

Hence the roots of the equation are \frac{-1 \pm i\sqrt{7} i }{2\sqrt{2}}

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Question 24: \sqrt{5} x^2 + x + \sqrt{5} = 0

Answer:

\sqrt{5} x^2 + x + \sqrt{5} = 0

Comparing the given equation with general form of quadratic equation ax^2 + bx + c = 0 we get,

\Rightarrow a = \sqrt{5},  \ b= 1  \text{ and } c = \sqrt{5}

Substituting these values in

\alpha = \frac{-b + \sqrt{b^2 - 4ac} }{2a}   and  \beta = \frac{-b - \sqrt{b^2 - 4ac} }{2a}

\Rightarrow \alpha = \frac{-1 + \sqrt{1 - 4 \times \sqrt{5} \times \sqrt{5}} }{2 \times \sqrt{5}}   and  \beta = \frac{-1 - \sqrt{1 - 4 \times \sqrt{5} \times \sqrt{5}} }{2 \times \sqrt{5}}

\Rightarrow \alpha = \frac{-1 + \sqrt{-19} }{2\sqrt{5}}   and  \beta = \frac{-1 - \sqrt{-19} }{2\sqrt{5}}

\Rightarrow \alpha = \frac{-1 + \sqrt{19} i }{2\sqrt{5}}   and  \beta = \frac{-1 - \sqrt{19} i }{2\sqrt{5}}

Hence the roots of the equation are \frac{-1 \pm \sqrt{19} i }{2\sqrt{5}}

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Question 25: -x^2 + x - 2 = 0

Answer:

-x^2 + x - 2 = 0

Comparing the given equation with general form of quadratic equation ax^2 + bx + c = 0 we get,

\Rightarrow a = -1,  \ b= 1  \text{ and } c = -2

Substituting these values in

\alpha = \frac{-b + \sqrt{b^2 - 4ac} }{2a}   and  \beta = \frac{-b - \sqrt{b^2 - 4ac} }{2a}

\Rightarrow \alpha = \frac{-1 + \sqrt{1 - 4 \times (-1) \times (-2)} }{2 \times (-1)}   and  \beta = \frac{-1 - \sqrt{-1 - 4 \times (-1) \times (-1)} }{2 \times (-1)}

\Rightarrow \alpha = \frac{-1 + \sqrt{-7} }{-2}   and  \beta = \frac{-1 - \sqrt{-7} }{-2}

\Rightarrow \alpha = \frac{-1 + \sqrt{7} i }{-2}   and  \beta = \frac{-1 - \sqrt{7} i }{-2}

Hence the roots of the equation are \frac{-1 \pm \sqrt{7} i }{-2} or \frac{1 \mp \sqrt{7} i }{2}

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Question 26: x^2 - 2 x + \frac{3}{2} = 0

Answer:

x^2 - 2 x + \frac{3}{2} = 0

Comparing the given equation with general form of quadratic equation ax^2 + bx + c = 0 we get,

\Rightarrow a = 1,  \ b= -2  \text{ and } c = \frac{3}{2}

Substituting these values in

\alpha = \frac{-b + \sqrt{b^2 - 4ac} }{2a}   and  \beta = \frac{-b - \sqrt{b^2 - 4ac} }{2a}

\Rightarrow \alpha = \frac{2 + \sqrt{(-2)^2 - 4 \times 1 \times (\frac{3}{2})} }{2 \times 1}   and \frac{2 - \sqrt{(-2)^2 - 4 \times 1 \times (\frac{3}{2})} }{2 \times 1}

\Rightarrow \alpha = \frac{2 + \sqrt{-2} }{2}   and  \beta = \frac{2 - \sqrt{-2} }{2}

\Rightarrow \alpha = \frac{2 + \sqrt{2} i }{2}   and  \beta = \frac{2 - \sqrt{2} i }{2}

\Rightarrow \alpha = 1 + \frac{1}{\sqrt{2}} i and 1 - \frac{1}{\sqrt{2}} i

Hence the roots of the equation are 1 + \frac{1}{\sqrt{2}} i and 1 - \frac{1}{\sqrt{2}} i

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Question 27: 3x^2 - 4x + \frac{20}{3} = 0

Answer:

3x^2 - 4x + \frac{20}{3} = 0

Comparing the given equation with general form of quadratic equation ax^2 + bx + c = 0 we get,

\Rightarrow a = 3,  \ b= -4  \text{ and } c = \frac{20}{3}

Substituting these values in

\alpha = \frac{-b + \sqrt{b^2 - 4ac} }{2a}   and  \beta = \frac{-b - \sqrt{b^2 - 4ac} }{2a}

\Rightarrow \alpha = \frac{4 + \sqrt{16 - 4 \times 3 \times \frac{20}{3} } }{2 \times 3}   and  \beta = \frac{4 - \sqrt{16 - 4 \times 3 \times \frac{20}{3}} }{2 \times 3}

\Rightarrow \alpha = \frac{4 + \sqrt{-64} }{6}   and  \beta = \frac{4 - \sqrt{-64} }{6}

\Rightarrow \alpha = \frac{4 + 8 i }{6}   and  \beta = \frac{4 - 8i }{6}

\Rightarrow \alpha = \frac{2 + 4 i }{3}   and  \beta = \frac{2 - 4i }{3}

Hence the roots of the equation are \beta = \frac{2 \pm 4i }{3}