18=a(a-7)

Solution for 18=a(a-7) equation:

Simplifying
18 = a(a + -7)

Reorder the terms:
18 = a(-7 + a)
18 = (-7 * a + a * a)
18 = (-7a + a2)

Solving
18 = -7a + a2

Solving for variable 'a'.

Reorder the terms:
18 + 7a + -1a2 = -7a + 7a + a2 + -1a2

Combine like terms: -7a + 7a = 0
18 + 7a + -1a2 = 0 + a2 + -1a2
18 + 7a + -1a2 = a2 + -1a2

Combine like terms: a2 + -1a2 = 0
18 + 7a + -1a2 = 0

Factor a trinomial.
(9 + -1a)(2 + 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 '(2 + a)' equal to zero and attempt to solve:

Simplifying
2 + a = 0

Solving
2 + a = 0

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

Add '-2' to each side of the equation.
2 + -2 + a = 0 + -2

Combine like terms: 2 + -2 = 0
0 + a = 0 + -2
a = 0 + -2

Combine like terms: 0 + -2 = -2
a = -2

Simplifying
a = -2
Solution
a = {9, -2}