(4m+7)(3m-8)=0

Solution for (4m+7)(3m-8)=0 equation:

(4m+7)(3m-8)=0

We multiply parentheses ..

(+12m^2-32m+21m-56)=0

We get rid of parentheses

12m^2-32m+21m-56=0

We add all the numbers together, and all the variables

12m^2-11m-56=0

a = 12; b = -11; c = -56;
Δ = b2-4ac
Δ = -112-4·12·(-56)
Δ = 2809
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$m_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$m_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2809}=53$
$m_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-11)-53}{2*12}=\frac{-42}{24}
=-1+3/4
$
$m_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-11)+53}{2*12}=\frac{64}{24}
=2+2/3
$