5x(x-9)=-15

Solution for 5x(x-9)=-15 equation:

5x(x-9)=-15

We move all terms to the left:

5x(x-9)-(-15)=0

We add all the numbers together, and all the variables

5x(x-9)+15=0

We multiply parentheses

5x^2-45x+15=0

a = 5; b = -45; c = +15;
Δ = b2-4ac
Δ = -452-4·5·15
Δ = 1725
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:

$\sqrt{\Delta}=\sqrt{1725}=\sqrt{25*69}=\sqrt{25}*\sqrt{69}=5\sqrt{69}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-45)-5\sqrt{69}}{2*5}=\frac{45-5\sqrt{69}}{10}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-45)+5\sqrt{69}}{2*5}=\frac{45+5\sqrt{69}}{10}
$