(7x-9)(9x+8)=

Solution for (7x-9)(9x+8)= equation:

(7x-9)(9x+8)=

We move all terms to the left:

(7x-9)(9x+8)-()=0

We add all the numbers together, and all the variables

(7x-9)(9x+8)=0

We multiply parentheses ..

(+63x^2+56x-81x-72)=0

We get rid of parentheses

63x^2+56x-81x-72=0

We add all the numbers together, and all the variables

63x^2-25x-72=0

a = 63; b = -25; c = -72;
Δ = b2-4ac
Δ = -252-4·63·(-72)
Δ = 18769
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{18769}=137$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-25)-137}{2*63}=\frac{-112}{126}
=-8/9
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-25)+137}{2*63}=\frac{162}{126}
=1+2/7
$