23=x^2-7

Solution for 23=x^2-7 equation:

23=x^2-7

We move all terms to the left:

23-(x^2-7)=0

We get rid of parentheses

-x^2+7+23=0

We add all the numbers together, and all the variables

-1x^2+30=0

a = -1; b = 0; c = +30;
Δ = b2-4ac
Δ = 02-4·(-1)·30
Δ = 120
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:

$\sqrt{\Delta}=\sqrt{120}=\sqrt{4*30}=\sqrt{4}*\sqrt{30}=2\sqrt{30}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-2\sqrt{30}}{2*-1}=\frac{0-2\sqrt{30}}{-2}
=-\frac{2\sqrt{30}}{-2}
=-\frac{\sqrt{30}}{-1}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+2\sqrt{30}}{2*-1}=\frac{0+2\sqrt{30}}{-2}
=\frac{2\sqrt{30}}{-2}
=\frac{\sqrt{30}}{-1}
$