(2x-7)(9x+9)=0

Solution for (2x-7)(9x+9)=0 equation:

(2x-7)(9x+9)=0

We multiply parentheses ..

(+18x^2+18x-63x-63)=0

We get rid of parentheses

18x^2+18x-63x-63=0

We add all the numbers together, and all the variables

18x^2-45x-63=0

a = 18; b = -45; c = -63;
Δ = b2-4ac
Δ = -452-4·18·(-63)
Δ = 6561
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{6561}=81$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-45)-81}{2*18}=\frac{-36}{36}
=-1
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-45)+81}{2*18}=\frac{126}{36}
=3+1/2
$