3x^2+12x+21=7

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Solution for 3x^2+12x+21=7 equation:


Simplifying
3x2 + 12x + 21 = 7

Reorder the terms:
21 + 12x + 3x2 = 7

Solving
21 + 12x + 3x2 = 7

Solving for variable 'x'.

Reorder the terms:
21 + -7 + 12x + 3x2 = 7 + -7

Combine like terms: 21 + -7 = 14
14 + 12x + 3x2 = 7 + -7

Combine like terms: 7 + -7 = 0
14 + 12x + 3x2 = 0

Begin completing the square.  Divide all terms by
3 the coefficient of the squared term: 

Divide each side by '3'.
4.666666667 + 4x + x2 = 0

Move the constant term to the right:

Add '-4.666666667' to each side of the equation.
4.666666667 + 4x + -4.666666667 + x2 = 0 + -4.666666667

Reorder the terms:
4.666666667 + -4.666666667 + 4x + x2 = 0 + -4.666666667

Combine like terms: 4.666666667 + -4.666666667 = 0.000000000
0.000000000 + 4x + x2 = 0 + -4.666666667
4x + x2 = 0 + -4.666666667

Combine like terms: 0 + -4.666666667 = -4.666666667
4x + x2 = -4.666666667

The x term is 4x.  Take half its coefficient (2).
Square it (4) and add it to both sides.

Add '4' to each side of the equation.
4x + 4 + x2 = -4.666666667 + 4

Reorder the terms:
4 + 4x + x2 = -4.666666667 + 4

Combine like terms: -4.666666667 + 4 = -0.666666667
4 + 4x + x2 = -0.666666667

Factor a perfect square on the left side:
(x + 2)(x + 2) = -0.666666667

Can't calculate square root of the right side.

The solution to this equation could not be determined.

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