3x^2-40+400=408

Solution for 3x^2-40+400=408 equation:

Simplifying
3x2 + -40 + 400 = 408

Reorder the terms:
-40 + 400 + 3x2 = 408

Combine like terms: -40 + 400 = 360
360 + 3x2 = 408

Solving
360 + 3x2 = 408

Solving for variable 'x'.

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

Add '-360' to each side of the equation.
360 + -360 + 3x2 = 408 + -360

Combine like terms: 360 + -360 = 0
0 + 3x2 = 408 + -360
3x2 = 408 + -360

Combine like terms: 408 + -360 = 48
3x2 = 48

Divide each side by '3'.
x2 = 16

Simplifying
x2 = 16

Take the square root of each side:
x = {-4, 4}