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NCERT Class XI Mathematics - Complex Numbers and Quadratic Equations - Solutions

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Question : 27 of 52
Marks: +1, -0
x2x^2 + 3x + 5 = 0
Solution:  
We have, x2x^2 + 3x + 5 = 0
Comparing the given equation with the general form ax2ax^2 + bx + c = 0,
we get a = 1, b = 3, c = 5.
∴ x = b±b24ac2a\frac{-b \pm \sqrt{b^2-4ac}}{2a}
= 3±(3)24×1×52\frac{-3 \pm \sqrt{(3)^2-4\times1\times5}}{2}
= 3±9202\frac{-3 \pm \sqrt{9-20}}{2} = 3±112\frac{-3 \pm \sqrt{-11}}{2} = 3±112\frac{-3 \pm \sqrt{11}}{2}
∴ The roots of the given equation are 3+112\frac{-3 + \sqrt{-11}}{2} and 3112\frac{-3 - \sqrt{-11}}{2}
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