(5x+5)(x+5)=25

Solution for (5x+5)(x+5)=25 equation:

(5x+5)(x+5)=25

We move all terms to the left:

(5x+5)(x+5)-(25)=0

We multiply parentheses ..

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

We get rid of parentheses

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

We add all the numbers together, and all the variables

5x^2+30x=0

a = 5; b = 30; c = 0;
Δ = b2-4ac
Δ = 302-4·5·0
Δ = 900
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{900}=30$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(30)-30}{2*5}=\frac{-60}{10}
=-6
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(30)+30}{2*5}=\frac{0}{10}
=0
$