-6x(2x-1)=-90

Solution for -6x(2x-1)=-90 equation:

-6x(2x-1)=-90

We move all terms to the left:

-6x(2x-1)-(-90)=0

We add all the numbers together, and all the variables

-6x(2x-1)+90=0

We multiply parentheses

-12x^2+6x+90=0

a = -12; b = 6; c = +90;
Δ = b2-4ac
Δ = 62-4·(-12)·90
Δ = 4356
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{4356}=66$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(6)-66}{2*-12}=\frac{-72}{-24}
=+3
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(6)+66}{2*-12}=\frac{60}{-24}
=-2+1/2
$