x^2-42x-135=0

Solution for x^2-42x-135=0 equation:

x^2-42x-135=0

a = 1; b = -42; c = -135;
Δ = b2-4ac
Δ = -422-4·1·(-135)
Δ = 2304
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2304}=48$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-42)-48}{2*1}=\frac{-6}{2}
=-3
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-42)+48}{2*1}=\frac{90}{2}
=45
$