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Solve 2x^2 + x + 1 = 0.(a) \(\frac{-1±i\sqrt{7}}{4}\)(b) \(\frac{1±i\sqrt{7}}{4}\)(c) \(\frac{1±\sqrt{7}}{4}\)(d) \(\frac{-1±\sqrt{7}}{4}\)I have been asked this question in unit test.Question is taken from Quadratic Equations topic in portion Complex Numbers and Quadratic Equations of Mathematics – Class 11

Answer»

Correct ANSWER is (a) \(\frac{-1±i\sqrt{7}}{4}\)

Easy explanation: 2x^2 + x + 1 = 0

D=1^2-4*2*1 = 1-8 = -7 ≤ 0.

Since D ≤ 0, IMAGINARY ROOTS are there.

=>x = \(\frac{-1±\sqrt{1^2-4 ˙ 2.1}}{2.2} = \frac{-1±i\sqrt{7}}{4}\).



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