9x(2x+6)=28

Solution for 9x(2x+6)=28 equation:

9x(2x+6)=28

We move all terms to the left:

9x(2x+6)-(28)=0

We multiply parentheses

18x^2+54x-28=0

a = 18; b = 54; c = -28;
Δ = b2-4ac
Δ = 542-4·18·(-28)
Δ = 4932
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:

$\sqrt{\Delta}=\sqrt{4932}=\sqrt{36*137}=\sqrt{36}*\sqrt{137}=6\sqrt{137}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(54)-6\sqrt{137}}{2*18}=\frac{-54-6\sqrt{137}}{36}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(54)+6\sqrt{137}}{2*18}=\frac{-54+6\sqrt{137}}{36}
$