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

Solution for -5x^2-5x=x^2+2x=0 equation:

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

We move all terms to the left:

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

We get rid of parentheses

-5x^2-x^2-5x-2x=0

We add all the numbers together, and all the variables

-6x^2-7x=0

a = -6; b = -7; c = 0;
Δ = b2-4ac
Δ = -72-4·(-6)·0
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{-(-7)-7}{2*-6}=\frac{0}{-12}
=0
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-7)+7}{2*-6}=\frac{14}{-12}
=-1+1/6
$