-28x-21=7x^2

Solution for -28x-21=7x^2 equation:

Simplifying
-28x + -21 = 7x2

Reorder the terms:
-21 + -28x = 7x2

Solving
-21 + -28x = 7x2

Solving for variable 'x'.

Combine like terms: 7x2 + -7x2 = 0
-21 + -28x + -7x2 = 0

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

Factor a trinomial.
-7((3 + x)(1 + x)) = 0

Ignore the factor -7.
Subproblem 1
Set the factor '(3 + x)' equal to zero and attempt to solve:

Simplifying
3 + x = 0

Solving
3 + x = 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 + x = 0 + -3

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

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

Simplifying
x = -3
Subproblem 2
Set the factor '(1 + x)' equal to zero and attempt to solve:

Simplifying
1 + x = 0

Solving
1 + x = 0

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

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

Combine like terms: 1 + -1 = 0
0 + x = 0 + -1
x = 0 + -1

Combine like terms: 0 + -1 = -1
x = -1

Simplifying
x = -1
Solution
x = {-3, -1}