-8x(-7x+9)=-11

Solution for -8x(-7x+9)=-11 equation:

-8x(-7x+9)=-11

We move all terms to the left:

-8x(-7x+9)-(-11)=0

We add all the numbers together, and all the variables

-8x(-7x+9)+11=0

We multiply parentheses

56x^2-72x+11=0

a = 56; b = -72; c = +11;
Δ = b2-4ac
Δ = -722-4·56·11
Δ = 2720
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{2720}=\sqrt{16*170}=\sqrt{16}*\sqrt{170}=4\sqrt{170}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-72)-4\sqrt{170}}{2*56}=\frac{72-4\sqrt{170}}{112}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-72)+4\sqrt{170}}{2*56}=\frac{72+4\sqrt{170}}{112}
$