Question

Solve $x^2+7x=7$ and give your answer correct to two decimal places.

Answer 1

Given:

$x^2+7x=7$

$x^2+7x-7=0$

Using quadratic formula:

$$\begin{gathered} x=\frac{-b\pm \sqrt{b^2-4ac}}{2a} \\ x=\frac{-7\pm \sqrt{49+28}}{2} \\ x=\frac{-7\pm \sqrt{77}}{2} \\ x=\frac{-7\pm 8.775}{2} \\ x=0.8875or-7.8875 \\ x=0.89or-7.89(twodecimalplaces) \end{gathered}$$

Hence, the value of $x$ is $0.89$ or $-7.89$