42x^2-90x-108=0

Solution for 42x^2-90x-108=0 equation:

42x^2-90x-108=0

a = 42; b = -90; c = -108;
Δ = b2-4ac
Δ = -902-4·42·(-108)
Δ = 26244
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{26244}=162$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-90)-162}{2*42}=\frac{-72}{84}
=-6/7
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-90)+162}{2*42}=\frac{252}{84}
=3
$