400=4x(x)

Solution for 400=4x(x) equation:

Simplifying
400 = 4x(x)

Multiply x * x
400 = 4x2

Solving
400 = 4x2

Solving for variable 'x'.

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

Add '-4x2' to each side of the equation.
400 + -4x2 = 4x2 + -4x2

Combine like terms: 4x2 + -4x2 = 0
400 + -4x2 = 0

Add '-400' to each side of the equation.
400 + -400 + -4x2 = 0 + -400

Combine like terms: 400 + -400 = 0
0 + -4x2 = 0 + -400
-4x2 = 0 + -400

Combine like terms: 0 + -400 = -400
-4x2 = -400

Divide each side by '-4'.
x2 = 100

Simplifying
x2 = 100

Take the square root of each side:
x = {-10, 10}