4x^2-21+20=0

Solution for 4x^2-21+20=0 equation:

Simplifying
4x2 + -21 + 20 = 0

Reorder the terms:
-21 + 20 + 4x2 = 0

Combine like terms: -21 + 20 = -1
-1 + 4x2 = 0

Solving
-1 + 4x2 = 0

Solving for variable 'x'.

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

Add '1' to each side of the equation.
-1 + 1 + 4x2 = 0 + 1

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

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

Divide each side by '4'.
x2 = 0.25

Simplifying
x2 = 0.25

Take the square root of each side:
x = {-0.5, 0.5}