x^2-(3x)+21=12

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Solution for x^2-(3x)+21=12 equation:


Simplifying
x2 + -1(3x) + 21 = 12

Remove parenthesis around (3x)
x2 + -1 * 3x + 21 = 12

Multiply -1 * 3
x2 + -3x + 21 = 12

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

Solving
21 + -3x + x2 = 12

Solving for variable 'x'.

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

Combine like terms: 21 + -12 = 9
9 + -3x + x2 = 12 + -12

Combine like terms: 12 + -12 = 0
9 + -3x + x2 = 0

Begin completing the square.

Move the constant term to the right:

Add '-9' to each side of the equation.
9 + -3x + -9 + x2 = 0 + -9

Reorder the terms:
9 + -9 + -3x + x2 = 0 + -9

Combine like terms: 9 + -9 = 0
0 + -3x + x2 = 0 + -9
-3x + x2 = 0 + -9

Combine like terms: 0 + -9 = -9
-3x + x2 = -9

The x term is -3x.  Take half its coefficient (-1.5).
Square it (2.25) and add it to both sides.

Add '2.25' to each side of the equation.
-3x + 2.25 + x2 = -9 + 2.25

Reorder the terms:
2.25 + -3x + x2 = -9 + 2.25

Combine like terms: -9 + 2.25 = -6.75
2.25 + -3x + x2 = -6.75

Factor a perfect square on the left side:
(x + -1.5)(x + -1.5) = -6.75

Can't calculate square root of the right side.

The solution to this equation could not be determined.

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