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Mathematics

Solve the following equation using quadratic formula:

3x2 - 8x + 2 = 0

Quadratic Equations

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Answer

Comparing equation 3x2 - 8x + 2 = 0 with ax2 + bx + c = 0, we get :

a = 3, b = -8 and c = 2.

By formula,

x = b±b24ac2a\dfrac{-b \pm \sqrt{b^2 - 4ac}}{2a}

Substituting values we get :

x=(8)±(8)24×3×22×3=8±64246=8±406=8±4×106=8±2106=2(4±10)6=(4±10)3=4+103 or4103.\Rightarrow x = \dfrac{-(-8) \pm \sqrt{(-8)^2 - 4 \times 3 \times 2}}{2\times 3} \\[1em] = \dfrac{8 \pm \sqrt{64 - 24}}{6} \\[1em] = \dfrac{8 \pm \sqrt{40}}{6} \\[1em] = \dfrac{8 \pm \sqrt{4 \times 10}}{6} \\[1em] = \dfrac{8 \pm 2\sqrt{10}}{6} \\[1em] = \dfrac{2(4 \pm \sqrt{10})}{6} \\[1em] = \dfrac{(4 \pm \sqrt{10})}{3} \\[1em] = \dfrac{4 + \sqrt{10}}{3} \text{ or} \dfrac{4 - \sqrt{10}}{3}.

Hence, x={4+103,4103}x = \Big{\dfrac{4 + \sqrt{10}}{3}, \dfrac{4 - \sqrt{10}}{3}\Big}.

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