8=a^2+9a

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Solution for 8=a^2+9a equation:


Simplifying
8 = a2 + 9a

Reorder the terms:
8 = 9a + a2

Solving
8 = 9a + a2

Solving for variable 'a'.

Reorder the terms:
8 + -9a + -1a2 = 9a + -9a + a2 + -1a2

Combine like terms: 9a + -9a = 0
8 + -9a + -1a2 = 0 + a2 + -1a2
8 + -9a + -1a2 = a2 + -1a2

Combine like terms: a2 + -1a2 = 0
8 + -9a + -1a2 = 0

Begin completing the square.  Divide all terms by
-1 the coefficient of the squared term: 

Divide each side by '-1'.
-8 + 9a + a2 = 0

Move the constant term to the right:

Add '8' to each side of the equation.
-8 + 9a + 8 + a2 = 0 + 8

Reorder the terms:
-8 + 8 + 9a + a2 = 0 + 8

Combine like terms: -8 + 8 = 0
0 + 9a + a2 = 0 + 8
9a + a2 = 0 + 8

Combine like terms: 0 + 8 = 8
9a + a2 = 8

The a term is 9a.  Take half its coefficient (4.5).
Square it (20.25) and add it to both sides.

Add '20.25' to each side of the equation.
9a + 20.25 + a2 = 8 + 20.25

Reorder the terms:
20.25 + 9a + a2 = 8 + 20.25

Combine like terms: 8 + 20.25 = 28.25
20.25 + 9a + a2 = 28.25

Factor a perfect square on the left side:
(a + 4.5)(a + 4.5) = 28.25

Calculate the square root of the right side: 5.315072906

Break this problem into two subproblems by setting 
(a + 4.5) equal to 5.315072906 and -5.315072906.

Subproblem 1

a + 4.5 = 5.315072906 Simplifying a + 4.5 = 5.315072906 Reorder the terms: 4.5 + a = 5.315072906 Solving 4.5 + a = 5.315072906 Solving for variable 'a'. Move all terms containing a to the left, all other terms to the right. Add '-4.5' to each side of the equation. 4.5 + -4.5 + a = 5.315072906 + -4.5 Combine like terms: 4.5 + -4.5 = 0.0 0.0 + a = 5.315072906 + -4.5 a = 5.315072906 + -4.5 Combine like terms: 5.315072906 + -4.5 = 0.815072906 a = 0.815072906 Simplifying a = 0.815072906

Subproblem 2

a + 4.5 = -5.315072906 Simplifying a + 4.5 = -5.315072906 Reorder the terms: 4.5 + a = -5.315072906 Solving 4.5 + a = -5.315072906 Solving for variable 'a'. Move all terms containing a to the left, all other terms to the right. Add '-4.5' to each side of the equation. 4.5 + -4.5 + a = -5.315072906 + -4.5 Combine like terms: 4.5 + -4.5 = 0.0 0.0 + a = -5.315072906 + -4.5 a = -5.315072906 + -4.5 Combine like terms: -5.315072906 + -4.5 = -9.815072906 a = -9.815072906 Simplifying a = -9.815072906

Solution

The solution to the problem is based on the solutions from the subproblems. a = {0.815072906, -9.815072906}

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