5x(x+5)=30

Solution for 5x(x+5)=30 equation:

5x(x+5)=30

We move all terms to the left:

5x(x+5)-(30)=0

We multiply parentheses

5x^2+25x-30=0

a = 5; b = 25; c = -30;
Δ = b2-4ac
Δ = 252-4·5·(-30)
Δ = 1225
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1225}=35$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(25)-35}{2*5}=\frac{-60}{10}
=-6
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(25)+35}{2*5}=\frac{10}{10}
=1
$