4(x^2+18x-225)=0

Solution for 4(x^2+18x-225)=0 equation:

4(x^2+18x-225)=0

We multiply parentheses

4x^2+72x-900=0

a = 4; b = 72; c = -900;
Δ = b2-4ac
Δ = 722-4·4·(-900)
Δ = 19584
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{19584}=\sqrt{576*34}=\sqrt{576}*\sqrt{34}=24\sqrt{34}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(72)-24\sqrt{34}}{2*4}=\frac{-72-24\sqrt{34}}{8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(72)+24\sqrt{34}}{2*4}=\frac{-72+24\sqrt{34}}{8}
$