3x(3x-4)=15+45

Solution for 3x(3x-4)=15+45 equation:

3x(3x-4)=15+45

We move all terms to the left:

3x(3x-4)-(15+45)=0

We add all the numbers together, and all the variables

3x(3x-4)-60=0

We multiply parentheses

9x^2-12x-60=0

a = 9; b = -12; c = -60;
Δ = b2-4ac
Δ = -122-4·9·(-60)
Δ = 2304
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2304}=48$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-12)-48}{2*9}=\frac{-36}{18}
=-2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-12)+48}{2*9}=\frac{60}{18}
=3+1/3
$