-90=-6x(4x+5)

Solution for -90=-6x(4x+5) equation:

-90=-6x(4x+5)

We move all terms to the left:

-90-(-6x(4x+5))=0


We calculate terms in parentheses: -(-6x(4x+5)), so:

-6x(4x+5)

We multiply parentheses

-24x^2-30x

Back to the equation:

-(-24x^2-30x)


We get rid of parentheses

24x^2+30x-90=0

a = 24; b = 30; c = -90;
Δ = b2-4ac
Δ = 302-4·24·(-90)
Δ = 9540
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{9540}=\sqrt{36*265}=\sqrt{36}*\sqrt{265}=6\sqrt{265}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(30)-6\sqrt{265}}{2*24}=\frac{-30-6\sqrt{265}}{48}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(30)+6\sqrt{265}}{2*24}=\frac{-30+6\sqrt{265}}{48}
$