9=a(a-8)

Solution for 9=a(a-8) equation:

Simplifying
9 = a(a + -8)

Reorder the terms:
9 = a(-8 + a)
9 = (-8 * a + a * a)
9 = (-8a + a2)

Solving
9 = -8a + a2

Solving for variable 'a'.

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

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

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

Factor a trinomial.
(9 + -1a)(1 + a) = 0

Subproblem 1
Set the factor '(9 + -1a)' equal to zero and attempt to solve:

Simplifying
9 + -1a = 0

Solving
9 + -1a = 0

Move all terms containing a to the left, all other terms to the right.

Add '-9' to each side of the equation.
9 + -9 + -1a = 0 + -9

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

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

Divide each side by '-1'.
a = 9

Simplifying
a = 9
Subproblem 2
Set the factor '(1 + a)' equal to zero and attempt to solve:

Simplifying
1 + a = 0

Solving
1 + a = 0

Move all terms containing a to the left, all other terms to the right.

Add '-1' to each side of the equation.
1 + -1 + a = 0 + -1

Combine like terms: 1 + -1 = 0
0 + a = 0 + -1
a = 0 + -1

Combine like terms: 0 + -1 = -1
a = -1

Simplifying
a = -1
Solution
a = {9, -1}