7x^2+12x+21=0

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Solution for 7x^2+12x+21=0 equation:


Simplifying
7x2 + 12x + 21 = 0

Reorder the terms:
21 + 12x + 7x2 = 0

Solving
21 + 12x + 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 + 1.714285714x + x2 = 0

Move the constant term to the right:

Add '-3' to each side of the equation.
3 + 1.714285714x + -3 + x2 = 0 + -3

Reorder the terms:
3 + -3 + 1.714285714x + x2 = 0 + -3

Combine like terms: 3 + -3 = 0
0 + 1.714285714x + x2 = 0 + -3
1.714285714x + x2 = 0 + -3

Combine like terms: 0 + -3 = -3
1.714285714x + x2 = -3

The x term is 1.714285714x.  Take half its coefficient (0.857142857).
Square it (0.7346938773) and add it to both sides.

Add '0.7346938773' to each side of the equation.
1.714285714x + 0.7346938773 + x2 = -3 + 0.7346938773

Reorder the terms:
0.7346938773 + 1.714285714x + x2 = -3 + 0.7346938773

Combine like terms: -3 + 0.7346938773 = -2.2653061227
0.7346938773 + 1.714285714x + x2 = -2.2653061227

Factor a perfect square on the left side:
(x + 0.857142857)(x + 0.857142857) = -2.2653061227

Can't calculate square root of the right side.

The solution to this equation could not be determined.

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