How do you solve x^2 – 7x – 1 = -7 using the quadratic formula?

1 Answer
Feb 16, 2016

Solution is $6$ and $1$

Explanation:

For an equation $a {x}^{2} + b x + c = 0$, quadratic formula gives the solution as $\frac{- b \pm \sqrt{{b}^{2} - 4 a c}}{2 a}$.

As in the given equation ${x}^{2} - 7 x - 1 = - 7$ or ${x}^{2} - 7 x + 6 = 0$ i.e. $a = 1 , b = - 7$ and $c = 6$

Solution is given by $\frac{- \left(- 7\right) \pm \sqrt{{\left(- 7\right)}^{2} - 4 \cdot 1.6}}{2 \cdot 1}$ or

$\frac{7 \pm \sqrt{49 - 24}}{2}$ or $\frac{7 \pm \sqrt{25}}{2}$ or $\frac{7 \pm 5}{2}$

Hence solution is $6$ and $1$