(4x+2x+4x)(5x+2x+9x)=90

Solution for (4x+2x+4x)(5x+2x+9x)=90 equation:

(4x+2x+4x)(5x+2x+9x)=90

We move all terms to the left:

(4x+2x+4x)(5x+2x+9x)-(90)=0

We add all the numbers together, and all the variables

(+10x)(+16x)-90=0

We multiply parentheses ..

(+160x^2)-90=0

We get rid of parentheses

160x^2-90=0

a = 160; b = 0; c = -90;
Δ = b2-4ac
Δ = 02-4·160·(-90)
Δ = 57600
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{57600}=240$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-240}{2*160}=\frac{-240}{320}
=-3/4
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+240}{2*160}=\frac{240}{320}
=3/4
$