7x(x+90)=180

Solution for 7x(x+90)=180 equation:

7x(x+90)=180

We move all terms to the left:

7x(x+90)-(180)=0

We multiply parentheses

7x^2+630x-180=0

a = 7; b = 630; c = -180;
Δ = b2-4ac
Δ = 6302-4·7·(-180)
Δ = 401940
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:

$\sqrt{\Delta}=\sqrt{401940}=\sqrt{36*11165}=\sqrt{36}*\sqrt{11165}=6\sqrt{11165}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(630)-6\sqrt{11165}}{2*7}=\frac{-630-6\sqrt{11165}}{14}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(630)+6\sqrt{11165}}{2*7}=\frac{-630+6\sqrt{11165}}{14}
$