(x+2)(x-1)=3x

Solution for (x+2)(x-1)=3x equation:

(x+2)(x-1)=3x

We move all terms to the left:

(x+2)(x-1)-(3x)=0

We add all the numbers together, and all the variables

-3x+(x+2)(x-1)=0

We multiply parentheses ..

(+x^2-1x+2x-2)-3x=0

We get rid of parentheses

x^2-1x+2x-3x-2=0

We add all the numbers together, and all the variables

x^2-2x-2=0

a = 1; b = -2; c = -2;
Δ = b2-4ac
Δ = -22-4·1·(-2)
Δ = 12
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{12}=\sqrt{4*3}=\sqrt{4}*\sqrt{3}=2\sqrt{3}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-2)-2\sqrt{3}}{2*1}=\frac{2-2\sqrt{3}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-2)+2\sqrt{3}}{2*1}=\frac{2+2\sqrt{3}}{2}
$