(9x-3)(7x+4)=0

Solution for (9x-3)(7x+4)=0 equation:

(9x-3)(7x+4)=0

We multiply parentheses ..

(+63x^2+36x-21x-12)=0

We get rid of parentheses

63x^2+36x-21x-12=0

We add all the numbers together, and all the variables

63x^2+15x-12=0

a = 63; b = 15; c = -12;
Δ = b2-4ac
Δ = 152-4·63·(-12)
Δ = 3249
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{3249}=57$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(15)-57}{2*63}=\frac{-72}{126}
=-4/7
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(15)+57}{2*63}=\frac{42}{126}
=1/3
$