0=7x^2+72x+90

Solution for 0=7x^2+72x+90 equation:

0=7x^2+72x+90

We move all terms to the left:

0-(7x^2+72x+90)=0

We add all the numbers together, and all the variables

-(7x^2+72x+90)=0

We get rid of parentheses

-7x^2-72x-90=0

a = -7; b = -72; c = -90;
Δ = b2-4ac
Δ = -722-4·(-7)·(-90)
Δ = 2664
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:

$\sqrt{\Delta}=\sqrt{2664}=\sqrt{36*74}=\sqrt{36}*\sqrt{74}=6\sqrt{74}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-72)-6\sqrt{74}}{2*-7}=\frac{72-6\sqrt{74}}{-14}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-72)+6\sqrt{74}}{2*-7}=\frac{72+6\sqrt{74}}{-14}
$