(4x^2+40x=9x^2)-9x^2

Solution for (4x^2+40x=9x^2)-9x^2 equation:

(4x^2+40x=9x^2)-9x^2

We move all terms to the left:

(4x^2+40x-(9x^2)-9x^2)=0

We get rid of parentheses

4x^2-9x^2-9x^2+40x=0

We add all the numbers together, and all the variables

-14x^2+40x=0

a = -14; b = 40; c = 0;
Δ = b2-4ac
Δ = 402-4·(-14)·0
Δ = 1600
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1600}=40$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(40)-40}{2*-14}=\frac{-80}{-28}
=2+6/7
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(40)+40}{2*-14}=\frac{0}{-28}
=0
$