# How do you solve x^2 -4x -5=0?

Jun 28, 2015

The solutions are
color(blue)(x=5, x=-1

#### Explanation:

${x}^{2} - 4 x - 5 = 0$

We can first factorise this expression by splitting the middle term and then find the solutions:

${x}^{2} \textcolor{b l u e}{- 5 x + 1 x} - 5 = 0$

$x \left(x - 5\right) + 1 \left(x - 5\right) = 0$
=color(blue)((x-5)(x+1)

Equating the factors with zero to obtain the solutions:

• x-5 = 0 , color(blue) (x=5
• x+1 = 0, color(blue)(x=-1