x=3x^2-15x-30

Solution for x=3x^2-15x-30 equation:

x=3x^2-15x-30

We move all terms to the left:

x-(3x^2-15x-30)=0

We get rid of parentheses

-3x^2+x+15x+30=0

We add all the numbers together, and all the variables

-3x^2+16x+30=0

a = -3; b = 16; c = +30;
Δ = b2-4ac
Δ = 162-4·(-3)·30
Δ = 616
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:

$\sqrt{\Delta}=\sqrt{616}=\sqrt{4*154}=\sqrt{4}*\sqrt{154}=2\sqrt{154}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(16)-2\sqrt{154}}{2*-3}=\frac{-16-2\sqrt{154}}{-6}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(16)+2\sqrt{154}}{2*-3}=\frac{-16+2\sqrt{154}}{-6}
$