4x-3x(3x+1)=-126

Solution for 4x-3x(3x+1)=-126 equation:

4x-3x(3x+1)=-126

We move all terms to the left:

4x-3x(3x+1)-(-126)=0

We add all the numbers together, and all the variables

4x-3x(3x+1)+126=0

We multiply parentheses

-9x^2+4x-3x+126=0

We add all the numbers together, and all the variables

-9x^2+x+126=0

a = -9; b = 1; c = +126;
Δ = b2-4ac
Δ = 12-4·(-9)·126
Δ = 4537
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{-(1)-\sqrt{4537}}{2*-9}=\frac{-1-\sqrt{4537}}{-18}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1)+\sqrt{4537}}{2*-9}=\frac{-1+\sqrt{4537}}{-18}
$