28x^3+21x^2=0

Solution for 28x^3+21x^2=0 equation:

Simplifying
28x3 + 21x2 = 0

Reorder the terms:
21x2 + 28x3 = 0

Solving
21x2 + 28x3 = 0

Solving for variable 'x'.

Factor out the Greatest Common Factor (GCF), '7x2'.
7x2(3 + 4x) = 0

Ignore the factor 7.
Subproblem 1
Set the factor 'x2' equal to zero and attempt to solve:

Simplifying
x2 = 0

Solving
x2 = 0

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

Simplifying
x2 = 0

Take the square root of each side:
x = {0}
Subproblem 2
Set the factor '(3 + 4x)' equal to zero and attempt to solve:

Simplifying
3 + 4x = 0

Solving
3 + 4x = 0

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

Add '-3' to each side of the equation.
3 + -3 + 4x = 0 + -3

Combine like terms: 3 + -3 = 0
0 + 4x = 0 + -3
4x = 0 + -3

Combine like terms: 0 + -3 = -3
4x = -3

Divide each side by '4'.
x = -0.75

Simplifying
x = -0.75
Solution
x = {0, -0.75}