.25x*x-1=15

Solution for .25x*x-1=15 equation:

Simplifying
0.25x * x + -1 = 15

Multiply x * x
0.25x2 + -1 = 15

Reorder the terms:
-1 + 0.25x2 = 15

Solving
-1 + 0.25x2 = 15

Solving for variable 'x'.

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

Add '1' to each side of the equation.
-1 + 1 + 0.25x2 = 15 + 1

Combine like terms: -1 + 1 = 0
0 + 0.25x2 = 15 + 1
0.25x2 = 15 + 1

Combine like terms: 15 + 1 = 16
0.25x2 = 16

Divide each side by '0.25'.
x2 = 64

Simplifying
x2 = 64

Take the square root of each side:
x = {-8, 8}