7x2+9-5=72

Solution for 7x2+9-5=72 equation:

7x^2+9-5=72

We move all terms to the left:

7x^2+9-5-(72)=0

We add all the numbers together, and all the variables

7x^2-68=0

a = 7; b = 0; c = -68;
Δ = b2-4ac
Δ = 02-4·7·(-68)
Δ = 1904
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:

$\sqrt{\Delta}=\sqrt{1904}=\sqrt{16*119}=\sqrt{16}*\sqrt{119}=4\sqrt{119}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-4\sqrt{119}}{2*7}=\frac{0-4\sqrt{119}}{14}
=-\frac{4\sqrt{119}}{14}
=-\frac{2\sqrt{119}}{7}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+4\sqrt{119}}{2*7}=\frac{0+4\sqrt{119}}{14}
=\frac{4\sqrt{119}}{14}
=\frac{2\sqrt{119}}{7}
$