-8x^2+84x=0

Solution for -8x^2+84x=0 equation:

Simplifying
-8x2 + 84x = 0

Reorder the terms:
84x + -8x2 = 0

Solving
84x + -8x2 = 0

Solving for variable 'x'.

Factor out the Greatest Common Factor (GCF), '4x'.
4x(21 + -2x) = 0

Ignore the factor 4.
Subproblem 1
Set the factor 'x' equal to zero and attempt to solve:

Simplifying
x = 0

Solving
x = 0

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

Simplifying
x = 0
Subproblem 2
Set the factor '(21 + -2x)' equal to zero and attempt to solve:

Simplifying
21 + -2x = 0

Solving
21 + -2x = 0

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

Add '-21' to each side of the equation.
21 + -21 + -2x = 0 + -21

Combine like terms: 21 + -21 = 0
0 + -2x = 0 + -21
-2x = 0 + -21

Combine like terms: 0 + -21 = -21
-2x = -21

Divide each side by '-2'.
x = 10.5

Simplifying
x = 10.5
Solution
x = {0, 10.5}