(4x-15)(7x+12)=0

Solution for (4x-15)(7x+12)=0 equation:

(4x-15)(7x+12)=0

We multiply parentheses ..

(+28x^2+48x-105x-180)=0

We get rid of parentheses

28x^2+48x-105x-180=0

We add all the numbers together, and all the variables

28x^2-57x-180=0

a = 28; b = -57; c = -180;
Δ = b2-4ac
Δ = -572-4·28·(-180)
Δ = 23409
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{23409}=153$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-57)-153}{2*28}=\frac{-96}{56}
=-1+5/7
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-57)+153}{2*28}=\frac{210}{56}
=3+3/4
$