7x^2-21=0

Solution for 7x^2-21=0 equation:

Simplifying
7x2 + -21 = 0

Reorder the terms:
-21 + 7x2 = 0

Solving
-21 + 7x2 = 0

Solving for variable 'x'.

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

Add '21' to each side of the equation.
-21 + 21 + 7x2 = 0 + 21

Combine like terms: -21 + 21 = 0
0 + 7x2 = 0 + 21
7x2 = 0 + 21

Combine like terms: 0 + 21 = 21
7x2 = 21

Divide each side by '7'.
x2 = 3

Simplifying
x2 = 3

Take the square root of each side:
x = {-1.732050808, 1.732050808}