-11m(-8m)-12m-(-8m)-(-8m)=13

Solution for -11m(-8m)-12m-(-8m)-(-8m)=13 equation:

-11m(-8m)-12m-(-8m)-(-8m)=13

We move all terms to the left:

-11m(-8m)-12m-(-8m)-(-8m)-(13)=0

We add all the numbers together, and all the variables

-12m-11m(-8m)-(-8m)-(-8m)-13=0

We multiply parentheses

88m^2-12m-(-8m)-(-8m)-13=0

We get rid of parentheses

88m^2-12m+8m+8m-13=0

We add all the numbers together, and all the variables

88m^2+4m-13=0

a = 88; b = 4; c = -13;
Δ = b2-4ac
Δ = 42-4·88·(-13)
Δ = 4592
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$m_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$m_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{4592}=\sqrt{16*287}=\sqrt{16}*\sqrt{287}=4\sqrt{287}$
$m_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(4)-4\sqrt{287}}{2*88}=\frac{-4-4\sqrt{287}}{176}
$
$m_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(4)+4\sqrt{287}}{2*88}=\frac{-4+4\sqrt{287}}{176}
$