3.14*r^2-100=0

Solution for 3.14*r^2-100=0 equation:

Simplifying
3.14r2 + -100 = 0

Reorder the terms:
-100 + 3.14r2 = 0

Solving
-100 + 3.14r2 = 0

Solving for variable 'r'.

Move all terms containing r to the left, all other terms to the right.

Add '100' to each side of the equation.
-100 + 100 + 3.14r2 = 0 + 100

Combine like terms: -100 + 100 = 0
0 + 3.14r2 = 0 + 100
3.14r2 = 0 + 100

Combine like terms: 0 + 100 = 100
3.14r2 = 100

Divide each side by '3.14'.
r2 = 31.84713376

Simplifying
r2 = 31.84713376

Take the square root of each side:
r = {-5.64332648, 5.64332648}