5x^2+8-21=0

Solution for 5x^2+8-21=0 equation:

Simplifying
5x2 + 8 + -21 = 0

Reorder the terms:
8 + -21 + 5x2 = 0

Combine like terms: 8 + -21 = -13
-13 + 5x2 = 0

Solving
-13 + 5x2 = 0

Solving for variable 'x'.

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

Add '13' to each side of the equation.
-13 + 13 + 5x2 = 0 + 13

Combine like terms: -13 + 13 = 0
0 + 5x2 = 0 + 13
5x2 = 0 + 13

Combine like terms: 0 + 13 = 13
5x2 = 13

Divide each side by '5'.
x2 = 2.6

Simplifying
x2 = 2.6

Take the square root of each side:
x = {-1.61245155, 1.61245155}