4x^2+6x+21=0

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Solution for 4x^2+6x+21=0 equation:


Simplifying
4x2 + 6x + 21 = 0

Reorder the terms:
21 + 6x + 4x2 = 0

Solving
21 + 6x + 4x2 = 0

Solving for variable 'x'.

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

Divide each side by '4'.
5.25 + 1.5x + x2 = 0

Move the constant term to the right:

Add '-5.25' to each side of the equation.
5.25 + 1.5x + -5.25 + x2 = 0 + -5.25

Reorder the terms:
5.25 + -5.25 + 1.5x + x2 = 0 + -5.25

Combine like terms: 5.25 + -5.25 = 0.00
0.00 + 1.5x + x2 = 0 + -5.25
1.5x + x2 = 0 + -5.25

Combine like terms: 0 + -5.25 = -5.25
1.5x + x2 = -5.25

The x term is 1.5x.  Take half its coefficient (0.75).
Square it (0.5625) and add it to both sides.

Add '0.5625' to each side of the equation.
1.5x + 0.5625 + x2 = -5.25 + 0.5625

Reorder the terms:
0.5625 + 1.5x + x2 = -5.25 + 0.5625

Combine like terms: -5.25 + 0.5625 = -4.6875
0.5625 + 1.5x + x2 = -4.6875

Factor a perfect square on the left side:
(x + 0.75)(x + 0.75) = -4.6875

Can't calculate square root of the right side.

The solution to this equation could not be determined.

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