84-3x^2=x^2

Solution for 84-3x^2=x^2 equation:

Simplifying
84 + -3x2 = x2

Solving
84 + -3x2 = x2

Solving for variable 'x'.

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

Add '-1x2' to each side of the equation.
84 + -3x2 + -1x2 = x2 + -1x2

Combine like terms: -3x2 + -1x2 = -4x2
84 + -4x2 = x2 + -1x2

Combine like terms: x2 + -1x2 = 0
84 + -4x2 = 0

Add '-84' to each side of the equation.
84 + -84 + -4x2 = 0 + -84

Combine like terms: 84 + -84 = 0
0 + -4x2 = 0 + -84
-4x2 = 0 + -84

Combine like terms: 0 + -84 = -84
-4x2 = -84

Divide each side by '-4'.
x2 = 21

Simplifying
x2 = 21

Take the square root of each side:
x = {-4.582575695, 4.582575695}