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Mathematics

Solve the following equation for x and give your answer correct to two decimal places :

2x2 - 10x + 5 = 0

Quadratic Equations

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Answer

Comparing 2x2 - 10x + 5 = 0 with ax2 + bx + c = 0 we get,

a = 2, b = -10 and c = 5.

We know that,

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

Substituting values of a, b and c in above equation we get,

x=(10)±(10)24.(2).(5)2(2)=10±100404=10±604=10±2154=10±7.744=10+7.744 and 107.744=17.744 and 2.264=4.44 and 0.56\Rightarrow x = \dfrac{-(-10) \pm \sqrt{(-10)^2 - 4.(2).(5)}}{2(2)} \\[1em] = \dfrac{10 \pm \sqrt{100 - 40}}{4} \\[1em] = \dfrac{10 \pm \sqrt{60}}{4} \\[1em] = \dfrac{10 \pm 2\sqrt{15}}{4} \\[1em] = \dfrac{10 \pm 7.74}{4} \\[1em] = \dfrac{10 + 7.74}{4} \text{ and } \dfrac{10 - 7.74}{4} \\[1em] = \dfrac{17.74}{4} \text{ and } \dfrac{2.26}{4} \\[1em] = 4.44 \text{ and } 0.56

Hence, x = 4.44 and 0.56

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