90x2-12=-42x

Solution for 90x2-12=-42x equation:

90x^2-12=-42x

We move all terms to the left:

90x^2-12-(-42x)=0

We get rid of parentheses

90x^2+42x-12=0

a = 90; b = 42; c = -12;
Δ = b2-4ac
Δ = 422-4·90·(-12)
Δ = 6084
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{6084}=78$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(42)-78}{2*90}=\frac{-120}{180}
=-2/3
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(42)+78}{2*90}=\frac{36}{180}
=1/5
$