(4x+15)(5x)=x

Solution for (4x+15)(5x)=x equation:

(4x+15)(5x)=x

We move all terms to the left:

(4x+15)(5x)-(x)=0

We add all the numbers together, and all the variables

-1x+(4x+15)5x=0

We multiply parentheses

20x^2-1x+75x=0

We add all the numbers together, and all the variables

20x^2+74x=0

a = 20; b = 74; c = 0;
Δ = b2-4ac
Δ = 742-4·20·0
Δ = 5476
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{5476}=74$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(74)-74}{2*20}=\frac{-148}{40}
=-3+7/10
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(74)+74}{2*20}=\frac{0}{40}
=0
$