21x^2-315=42x

Solution for 21x^2-315=42x equation:

Simplifying
21x2 + -315 = 42x

Reorder the terms:
-315 + 21x2 = 42x

Solving
-315 + 21x2 = 42x

Solving for variable 'x'.

Reorder the terms:
-315 + -42x + 21x2 = 42x + -42x

Combine like terms: 42x + -42x = 0
-315 + -42x + 21x2 = 0

Factor out the Greatest Common Factor (GCF), '21'.
21(-15 + -2x + x2) = 0

Factor a trinomial.
21((-3 + -1x)(5 + -1x)) = 0

Ignore the factor 21.
Subproblem 1
Set the factor '(-3 + -1x)' equal to zero and attempt to solve:

Simplifying
-3 + -1x = 0

Solving
-3 + -1x = 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 + -1x = 0 + 3

Combine like terms: -3 + 3 = 0
0 + -1x = 0 + 3
-1x = 0 + 3

Combine like terms: 0 + 3 = 3
-1x = 3

Divide each side by '-1'.
x = -3

Simplifying
x = -3
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 = {-3, 5}