55x-3x(9x+12)=-64

Solution for 55x-3x(9x+12)=-64 equation:

55x-3x(9x+12)=-64

We move all terms to the left:

55x-3x(9x+12)-(-64)=0

We add all the numbers together, and all the variables

55x-3x(9x+12)+64=0

We multiply parentheses

-27x^2+55x-36x+64=0

We add all the numbers together, and all the variables

-27x^2+19x+64=0

a = -27; b = 19; c = +64;
Δ = b2-4ac
Δ = 192-4·(-27)·64
Δ = 7273
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(19)-\sqrt{7273}}{2*-27}=\frac{-19-\sqrt{7273}}{-54}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(19)+\sqrt{7273}}{2*-27}=\frac{-19+\sqrt{7273}}{-54}
$