3x(1+x)=21+x

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Solution for 3x(1+x)=21+x equation: 


Simplifying
3x(1 + x) = 21 + x
(1 * 3x + x * 3x) = 21 + x
(3x + 3x2) = 21 + x

Solving
3x + 3x2 = 21 + x

Solving for variable 'x'.

Reorder the terms:
-21 + 3x + -1x + 3x2 = 21 + x + -21 + -1x

Combine like terms: 3x + -1x = 2x
-21 + 2x + 3x2 = 21 + x + -21 + -1x

Reorder the terms:
-21 + 2x + 3x2 = 21 + -21 + x + -1x

Combine like terms: 21 + -21 = 0
-21 + 2x + 3x2 = 0 + x + -1x
-21 + 2x + 3x2 = x + -1x

Combine like terms: x + -1x = 0
-21 + 2x + 3x2 = 0

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


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 '(7 + -3x)' equal to zero and attempt to solve:

Simplifying
7 + -3x = 0

Solving
7 + -3x = 0

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

Add '-7' to each side of the equation.
7 + -7 + -3x = 0 + -7

Combine like terms: 7 + -7 = 0
0 + -3x = 0 + -7
-3x = 0 + -7

Combine like terms: 0 + -7 = -7
-3x = -7

Divide each side by '-3'.
x = 2.333333333

Simplifying
x = 2.333333333
Solution
x = {-3, 2.333333333}

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