X(-2)=x2-4x

Solution for X(-2)=x2-4x equation:

X(-2)=X2-4X

We move all terms to the left:

X(-2)-(X2-4X)=0

We add all the numbers together, and all the variables

-(+X^2-4X)+X(-2)=0

We multiply parentheses

-(+X^2-4X)-2X=0

We get rid of parentheses

-X^2+4X-2X=0

We add all the numbers together, and all the variables

-1X^2+2X=0

a = -1; b = 2; c = 0;
Δ = b2-4ac
Δ = 22-4·(-1)·0
Δ = 4
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{4}=2$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(2)-2}{2*-1}=\frac{-4}{-2}
=+2
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(2)+2}{2*-1}=\frac{0}{-2}
=0
$