121=64+x^2

Solution for 121=64+x^2 equation:

121=64+x^2

We move all terms to the left:

121-(64+x^2)=0

We get rid of parentheses

-x^2-64+121=0

We add all the numbers together, and all the variables

-1x^2+57=0

a = -1; b = 0; c = +57;
Δ = b2-4ac
Δ = 02-4·(-1)·57
Δ = 228
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:

$\sqrt{\Delta}=\sqrt{228}=\sqrt{4*57}=\sqrt{4}*\sqrt{57}=2\sqrt{57}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-2\sqrt{57}}{2*-1}=\frac{0-2\sqrt{57}}{-2}
=-\frac{2\sqrt{57}}{-2}
=-\frac{\sqrt{57}}{-1}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+2\sqrt{57}}{2*-1}=\frac{0+2\sqrt{57}}{-2}
=\frac{2\sqrt{57}}{-2}
=\frac{\sqrt{57}}{-1}
$