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X 2 − X + 1 = 0 - Mathematics

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Question

\[x^2 - x + 1 = 0\]

Solution

We have:

\[x^2 - x + 1 = 0\]

\[ \Rightarrow x^2 - x + \frac{1}{2} + \frac{3}{4} = 0\]

\[ \Rightarrow x^2 - 2 \times x \times \frac{1}{2} + \left( \frac{1}{2} \right)^2 - \frac{3}{4} i^2 = 0\]

\[ \Rightarrow \left( x - \frac{1}{2} \right)^2 - \left( \frac{i\sqrt{3}}{2} \right)^2 = 0\]

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

\[\Rightarrow \left( x - \frac{1}{2} + \frac{i\sqrt{3}}{2} \right) = 0\]  or \[\left( x - \frac{1}{2} - \frac{i\sqrt{3}}{2} \right) = 0\]

\[\Rightarrow x = \frac{1}{2} - \frac{i\sqrt{3}}{2}\]   or \[x = \frac{1}{2} + \frac{i\sqrt{3}}{2}\]

Hence, the roots of the equation are 

\[\frac{1}{2} \pm \frac{i\sqrt{3}}{2} .\]
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Chapter 14: Quadratic Equations - Exercise 14.1 [Page 6]

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RD Sharma Mathematics [English] Class 11
Chapter 14 Quadratic Equations
Exercise 14.1 | Q 11 | Page 6

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