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

Solution for (x+5)(2-x)=0 equation:

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

We add all the numbers together, and all the variables

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

We multiply parentheses ..

(-1x^2+2x-5x+10)=0

We get rid of parentheses

-1x^2+2x-5x+10=0

We add all the numbers together, and all the variables

-1x^2-3x+10=0

a = -1; b = -3; c = +10;
Δ = b2-4ac
Δ = -32-4·(-1)·10
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{-(-3)-7}{2*-1}=\frac{-4}{-2}
=+2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-3)+7}{2*-1}=\frac{10}{-2}
=-5
$