7y^2+21y=0

Solution for 7y^2+21y=0 equation:

Simplifying
7y2 + 21y = 0

Reorder the terms:
21y + 7y2 = 0

Solving
21y + 7y2 = 0

Solving for variable 'y'.

Factor out the Greatest Common Factor (GCF), '7y'.
7y(3 + y) = 0

Ignore the factor 7.
Subproblem 1
Set the factor 'y' equal to zero and attempt to solve:

Simplifying
y = 0

Solving
y = 0

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

Simplifying
y = 0
Subproblem 2
Set the factor '(3 + y)' equal to zero and attempt to solve:

Simplifying
3 + y = 0

Solving
3 + y = 0

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

Add '-3' to each side of the equation.
3 + -3 + y = 0 + -3

Combine like terms: 3 + -3 = 0
0 + y = 0 + -3
y = 0 + -3

Combine like terms: 0 + -3 = -3
y = -3

Simplifying
y = -3
Solution
y = {0, -3}