X(4x+5)=90

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

X(4X+5)=90

We move all terms to the left:

X(4X+5)-(90)=0

We multiply parentheses

4X^2+5X-90=0

a = 4; b = 5; c = -90;
Δ = b2-4ac
Δ = 52-4·4·(-90)
Δ = 1465
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(5)-\sqrt{1465}}{2*4}=\frac{-5-\sqrt{1465}}{8}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(5)+\sqrt{1465}}{2*4}=\frac{-5+\sqrt{1465}}{8}
$