a^2-7a+21=0

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Solution for a^2-7a+21=0 equation:


Simplifying
a2 + -7a + 21 = 0

Reorder the terms:
21 + -7a + a2 = 0

Solving
21 + -7a + a2 = 0

Solving for variable 'a'.

Begin completing the square.

Move the constant term to the right:

Add '-21' to each side of the equation.
21 + -7a + -21 + a2 = 0 + -21

Reorder the terms:
21 + -21 + -7a + a2 = 0 + -21

Combine like terms: 21 + -21 = 0
0 + -7a + a2 = 0 + -21
-7a + a2 = 0 + -21

Combine like terms: 0 + -21 = -21
-7a + a2 = -21

The a term is -7a.  Take half its coefficient (-3.5).
Square it (12.25) and add it to both sides.

Add '12.25' to each side of the equation.
-7a + 12.25 + a2 = -21 + 12.25

Reorder the terms:
12.25 + -7a + a2 = -21 + 12.25

Combine like terms: -21 + 12.25 = -8.75
12.25 + -7a + a2 = -8.75

Factor a perfect square on the left side:
(a + -3.5)(a + -3.5) = -8.75

Can't calculate square root of the right side.

The solution to this equation could not be determined.

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