(x*x)+(2x*2x)=25

Solution for (x*x)+(2x*2x)=25 equation:

Simplifying
(x * x) + (2x * 2x) = 25

Multiply x * x
(x2) + (2x * 2x) = 25
x2 + (2x * 2x) = 25

Reorder the terms for easier multiplication:
x2 + (2 * 2x * x) = 25

Multiply 2 * 2
x2 + (4x * x) = 25

Multiply x * x
x2 + (4x2) = 25

Combine like terms: x2 + (4x2) = 5x2
5x2 = 25

Solving
5x2 = 25

Solving for variable 'x'.

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

Divide each side by '5'.
x2 = 5

Simplifying
x2 = 5

Take the square root of each side:
x = {-2.236067978, 2.236067978}