9x(x+10)=90

Solution for 9x(x+10)=90 equation:

9x(x+10)=90

We move all terms to the left:

9x(x+10)-(90)=0

We multiply parentheses

9x^2+90x-90=0

a = 9; b = 90; c = -90;
Δ = b2-4ac
Δ = 902-4·9·(-90)
Δ = 11340
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:

$\sqrt{\Delta}=\sqrt{11340}=\sqrt{324*35}=\sqrt{324}*\sqrt{35}=18\sqrt{35}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(90)-18\sqrt{35}}{2*9}=\frac{-90-18\sqrt{35}}{18}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(90)+18\sqrt{35}}{2*9}=\frac{-90+18\sqrt{35}}{18}
$