90=3x(4x-2)

Solution for 90=3x(4x-2) equation:

90=3x(4x-2)

We move all terms to the left:

90-(3x(4x-2))=0


We calculate terms in parentheses: -(3x(4x-2)), so:

3x(4x-2)

We multiply parentheses

12x^2-6x

Back to the equation:

-(12x^2-6x)


We get rid of 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
$