3(x^2+4x-135)=0

Solution for 3(x^2+4x-135)=0 equation:

3(x^2+4x-135)=0

We multiply parentheses

3x^2+12x-405=0

a = 3; b = 12; c = -405;
Δ = b2-4ac
Δ = 122-4·3·(-405)
Δ = 5004
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:

$\sqrt{\Delta}=\sqrt{5004}=\sqrt{36*139}=\sqrt{36}*\sqrt{139}=6\sqrt{139}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(12)-6\sqrt{139}}{2*3}=\frac{-12-6\sqrt{139}}{6}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(12)+6\sqrt{139}}{2*3}=\frac{-12+6\sqrt{139}}{6}
$