How do you solve $x^{2} - 4 x - 5 = 0$ $x^2 -4x -5=0$ ?

Question

7418 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2015-06-28T07:37:52

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

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

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

$x^{2} - 5 x + 1 x - 5 = 0$ $x^2 color(blue)(-5x +1x)-5=0$

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

Equating the factors with zero to obtain the solutions:

How do you solve x2−4x−5=0x^2 -4x -5=0?