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

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Question : 24 of 52
Marks: +1, -0
2x22x^2 + x + 1 = 0
Solution:  
We have, 2x22x^2 + x + 1 = 0
Comparing the given equation with the general form ax2ax^2 + bx + c = 0,
we get a = 2, b = 1, c = 1.
∴ x = b±b24ac2a\frac{-b\pm\sqrt{b^2-4ac}}{2a} = 1±(1)24×2×12×2\frac{-1\pm\sqrt{(1)^2-4\times2\times1}}{2\times2} = 1±184\frac{-1\pm\sqrt{1-8}}{4}
= 1±74\frac{-1\pm\sqrt{-7}}{4} = 1±7i4\frac{-1\pm\sqrt{7}i}{4}
∴ Roots of the given equation are 1+7i4\frac{-1+\sqrt{7}i}{4} and 17i4\frac{-1-\sqrt{7}i}{4}
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