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

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

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

We multiply parentheses ..

(+28x^2+36x-21x-27)=0

We get rid of parentheses

28x^2+36x-21x-27=0

We add all the numbers together, and all the variables

28x^2+15x-27=0

a = 28; b = 15; c = -27;
Δ = b2-4ac
Δ = 152-4·28·(-27)
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*28}=\frac{-72}{56}
=-1+2/7
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(15)+57}{2*28}=\frac{42}{56}
=3/4
$