-15x2-40x=-20x2-8x

Solution for -15x2-40x=-20x2-8x equation:

-15x^2-40x=-20x^2-8x

We move all terms to the left:

-15x^2-40x-(-20x^2-8x)=0

We get rid of parentheses

-15x^2+20x^2+8x-40x=0

We add all the numbers together, and all the variables

5x^2-32x=0

a = 5; b = -32; c = 0;
Δ = b2-4ac
Δ = -322-4·5·0
Δ = 1024
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1024}=32$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-32)-32}{2*5}=\frac{0}{10}
=0
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-32)+32}{2*5}=\frac{64}{10}
=6+2/5
$