(8x-1)(7x+9)=0

Solution for (8x-1)(7x+9)=0 equation:

(8x-1)(7x+9)=0

We multiply parentheses ..

(+56x^2+72x-7x-9)=0

We get rid of parentheses

56x^2+72x-7x-9=0

We add all the numbers together, and all the variables

56x^2+65x-9=0

a = 56; b = 65; c = -9;
Δ = b2-4ac
Δ = 652-4·56·(-9)
Δ = 6241
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{6241}=79$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(65)-79}{2*56}=\frac{-144}{112}
=-1+2/7
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(65)+79}{2*56}=\frac{14}{112}
=1/8
$