9x(2x-7)=28

Solution for 9x(2x-7)=28 equation:

9x(2x-7)=28

We move all terms to the left:

9x(2x-7)-(28)=0

We multiply parentheses

18x^2-63x-28=0

a = 18; b = -63; c = -28;
Δ = b2-4ac
Δ = -632-4·18·(-28)
Δ = 5985
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:

$\sqrt{\Delta}=\sqrt{5985}=\sqrt{9*665}=\sqrt{9}*\sqrt{665}=3\sqrt{665}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-63)-3\sqrt{665}}{2*18}=\frac{63-3\sqrt{665}}{36}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-63)+3\sqrt{665}}{2*18}=\frac{63+3\sqrt{665}}{36}
$