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

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

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

We add all the numbers together, and all the variables

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

We multiply parentheses ..

(-5x^2-2x+25x+10)=0

We get rid of parentheses

-5x^2-2x+25x+10=0

We add all the numbers together, and all the variables

-5x^2+23x+10=0

a = -5; b = 23; c = +10;
Δ = b2-4ac
Δ = 232-4·(-5)·10
Δ = 729
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{729}=27$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(23)-27}{2*-5}=\frac{-50}{-10}
=+5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(23)+27}{2*-5}=\frac{4}{-10}
=-2/5
$