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Mathematics

Solve the following equation for x, giving your answer correct to 3 decimal places :

x2 - 16x + 6 = 0

Quadratic Equations

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Answer

Comparing x2 - 16x + 6 = 0 with ax2 + bx + c = 0 we get,

a = 1, b = -16 and c = 6.

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=(16)±(16)24.(1).(6)2(1)=16±256242=16±2322=16±15.2322=16+15.2322 or 1615.2322=31.2322 or 0.7682=15.616 or 0.384\Rightarrow x = \dfrac{-(-16) \pm \sqrt{(-16)^2 - 4.(1).(6)}}{2(1)} \\[1em] = \dfrac{16 \pm \sqrt{256 - 24}}{2} \\[1em] = \dfrac{16 \pm \sqrt{232}}{2} \\[1em] = \dfrac{16 \pm 15.232}{2} \\[1em] = \dfrac{16 + 15.232}{2} \text{ or } \dfrac{16 - 15.232}{2} \\[1em] = \dfrac{31.232}{2} \text{ or } \dfrac{0.768}{2} \\[1em] = 15.616 \text{ or } 0.384

Hence, x = 15.616 or 0.384

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