3x(x+5)=13

Solution for 3x(x+5)=13 equation:

3x(x+5)=13

We move all terms to the left:

3x(x+5)-(13)=0

We multiply parentheses

3x^2+15x-13=0

a = 3; b = 15; c = -13;
Δ = b2-4ac
Δ = 152-4·3·(-13)
Δ = 381
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{-(15)-\sqrt{381}}{2*3}=\frac{-15-\sqrt{381}}{6}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(15)+\sqrt{381}}{2*3}=\frac{-15+\sqrt{381}}{6}
$