7x^2-28x+21=56

Solution for 7x^2-28x+21=56 equation:

Simplifying
7x2 + -28x + 21 = 56

Reorder the terms:
21 + -28x + 7x2 = 56

Solving
21 + -28x + 7x2 = 56

Solving for variable 'x'.

Reorder the terms:
21 + -56 + -28x + 7x2 = 56 + -56

Combine like terms: 21 + -56 = -35
-35 + -28x + 7x2 = 56 + -56

Combine like terms: 56 + -56 = 0
-35 + -28x + 7x2 = 0

Factor out the Greatest Common Factor (GCF), '7'.
7(-5 + -4x + x2) = 0

Factor a trinomial.
7((-1 + -1x)(5 + -1x)) = 0

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

Simplifying
-1 + -1x = 0

Solving
-1 + -1x = 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 + -1x = 0 + 1

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

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

Divide each side by '-1'.
x = -1

Simplifying
x = -1
Subproblem 2
Set the factor '(5 + -1x)' equal to zero and attempt to solve:

Simplifying
5 + -1x = 0

Solving
5 + -1x = 0

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

Add '-5' to each side of the equation.
5 + -5 + -1x = 0 + -5

Combine like terms: 5 + -5 = 0
0 + -1x = 0 + -5
-1x = 0 + -5

Combine like terms: 0 + -5 = -5
-1x = -5

Divide each side by '-1'.
x = 5

Simplifying
x = 5
Solution
x = {-1, 5}