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

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Question : 26 of 52
Marks: +1, -0
−x2-x^2 + x - 2 = 0
Solution:  
We have , −x2-x^2 + x - 2 = 0
Comparing the given equation with the general form ax2ax^2 + bx + c = 0,
we get a = –1, b = 1, c = –2.
∴ x = −b±b2−4ac2a\frac{-b \pm \sqrt{b^2 - 4ac}}{2a} = −1±(1)2−4×(−1)×(−2)2(−1)\frac{-1 \pm \sqrt{(1)^2 - 4 \times (-1) \times (-2)}}{2(-1)}
= −1±1−8−2\frac{-1 \pm \sqrt{1-8}}{-2} = −1±−7−2\frac{-1 \pm \sqrt{-7}}{-2} = −1±i7−2\frac{-1 \pm i\sqrt{7}}{-2}
∴ The roots of the given equation are −1+i7−2\frac{-1 + i\sqrt{7}}{-2} and −1−i7−2\frac{-1 - i\sqrt{7}}{-2}
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