X(3x+4)=16

Solution for X(3x+4)=16 equation:

X(3X+4)=16

We move all terms to the left:

X(3X+4)-(16)=0

We multiply parentheses

3X^2+4X-16=0

a = 3; b = 4; c = -16;
Δ = b2-4ac
Δ = 42-4·3·(-16)
Δ = 208
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:

$\sqrt{\Delta}=\sqrt{208}=\sqrt{16*13}=\sqrt{16}*\sqrt{13}=4\sqrt{13}$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(4)-4\sqrt{13}}{2*3}=\frac{-4-4\sqrt{13}}{6}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(4)+4\sqrt{13}}{2*3}=\frac{-4+4\sqrt{13}}{6}
$