(2x+5)*(2-x)=4

Solution for (2x+5)*(2-x)=4 equation:

(2x+5)(2-x)=4

We move all terms to the left:

(2x+5)(2-x)-(4)=0

We add all the numbers together, and all the variables

(2x+5)(-1x+2)-4=0

We multiply parentheses ..

(-2x^2+4x-5x+10)-4=0

We get rid of parentheses

-2x^2+4x-5x+10-4=0

We add all the numbers together, and all the variables

-2x^2-1x+6=0

a = -2; b = -1; c = +6;
Δ = b2-4ac
Δ = -12-4·(-2)·6
Δ = 49
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{49}=7$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-1)-7}{2*-2}=\frac{-6}{-4}
=1+1/2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-1)+7}{2*-2}=\frac{8}{-4}
=-2
$