21x^2+84x=0

Solution for 21x^2+84x=0 equation:

Simplifying
21x2 + 84x = 0

Reorder the terms:
84x + 21x2 = 0

Solving
84x + 21x2 = 0

Solving for variable 'x'.

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

Ignore the factor 21.
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 '(4 + x)' equal to zero and attempt to solve:

Simplifying
4 + x = 0

Solving
4 + x = 0

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

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

Combine like terms: 4 + -4 = 0
0 + x = 0 + -4
x = 0 + -4

Combine like terms: 0 + -4 = -4
x = -4

Simplifying
x = -4
Solution
x = {0, -4}