3x+7x^2+21=0

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Solution for 3x+7x^2+21=0 equation:


Simplifying
3x + 7x2 + 21 = 0

Reorder the terms:
21 + 3x + 7x2 = 0

Solving
21 + 3x + 7x2 = 0

Solving for variable 'x'.

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

Divide each side by '7'.
3 + 0.4285714286x + x2 = 0

Move the constant term to the right:

Add '-3' to each side of the equation.
3 + 0.4285714286x + -3 + x2 = 0 + -3

Reorder the terms:
3 + -3 + 0.4285714286x + x2 = 0 + -3

Combine like terms: 3 + -3 = 0
0 + 0.4285714286x + x2 = 0 + -3
0.4285714286x + x2 = 0 + -3

Combine like terms: 0 + -3 = -3
0.4285714286x + x2 = -3

The x term is 0.4285714286x.  Take half its coefficient (0.2142857143).
Square it (0.04591836735) and add it to both sides.

Add '0.04591836735' to each side of the equation.
0.4285714286x + 0.04591836735 + x2 = -3 + 0.04591836735

Reorder the terms:
0.04591836735 + 0.4285714286x + x2 = -3 + 0.04591836735

Combine like terms: -3 + 0.04591836735 = -2.95408163265
0.04591836735 + 0.4285714286x + x2 = -2.95408163265

Factor a perfect square on the left side:
(x + 0.2142857143)(x + 0.2142857143) = -2.95408163265

Can't calculate square root of the right side.

The solution to this equation could not be determined.

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