3x(x+15)=131

Solution for 3x(x+15)=131 equation:

3x(x+15)=131

We move all terms to the left:

3x(x+15)-(131)=0

We multiply parentheses

3x^2+45x-131=0

a = 3; b = 45; c = -131;
Δ = b2-4ac
Δ = 452-4·3·(-131)
Δ = 3597
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(45)-\sqrt{3597}}{2*3}=\frac{-45-\sqrt{3597}}{6}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(45)+\sqrt{3597}}{2*3}=\frac{-45+\sqrt{3597}}{6}
$