3x^2-9=78

Solution for 3x^2-9=78 equation:

Simplifying
3x2 + -9 = 78

Reorder the terms:
-9 + 3x2 = 78

Solving
-9 + 3x2 = 78

Solving for variable 'x'.

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

Add '9' to each side of the equation.
-9 + 9 + 3x2 = 78 + 9

Combine like terms: -9 + 9 = 0
0 + 3x2 = 78 + 9
3x2 = 78 + 9

Combine like terms: 78 + 9 = 87
3x2 = 87

Divide each side by '3'.
x2 = 29

Simplifying
x2 = 29

Take the square root of each side:
x = {-5.385164807, 5.385164807}