9x^2-30x+36=72

Solution for 9x^2-30x+36=72 equation:

9x^2-30x+36=72

We move all terms to the left:

9x^2-30x+36-(72)=0

We add all the numbers together, and all the variables

9x^2-30x-36=0

a = 9; b = -30; c = -36;
Δ = b2-4ac
Δ = -302-4·9·(-36)
Δ = 2196
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:

$\sqrt{\Delta}=\sqrt{2196}=\sqrt{36*61}=\sqrt{36}*\sqrt{61}=6\sqrt{61}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-30)-6\sqrt{61}}{2*9}=\frac{30-6\sqrt{61}}{18}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-30)+6\sqrt{61}}{2*9}=\frac{30+6\sqrt{61}}{18}
$