(x-2)(1+x)=4

Solution for (x-2)(1+x)=4 equation:

(x-2)(1+x)=4

We move all terms to the left:

(x-2)(1+x)-(4)=0

We add all the numbers together, and all the variables

(x-2)(x+1)-4=0

We multiply parentheses ..

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

We get rid of parentheses

x^2+x-2x-2-4=0

We add all the numbers together, and all the variables

x^2-1x-6=0

a = 1; b = -1; c = -6;
Δ = b2-4ac
Δ = -12-4·1·(-6)
Δ = 25
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{25}=5$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-1)-5}{2*1}=\frac{-4}{2}
=-2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-1)+5}{2*1}=\frac{6}{2}
=3
$