# How to use the discriminant to find out how many real number roots an equation has for -x^2 - 2x - 7 = -6?

##### 1 Answer
Jun 7, 2015

$y = - {x}^{2} - 2 x - 1 = 0$

You don't need to find D. Use shortcut. Since a - b + c = 0, one real

root is (-1) and the other is $\left(- \frac{c}{a} = - 1\right) .$

Note: y is a perfect square polynomial

y = -(x + 1)^2 --> double root --> x = -1