(a+3)(a-3)=0

Solution for (a+3)(a-3)=0 equation:

Simplifying
(a + 3)(a + -3) = 0

Reorder the terms:
(3 + a)(a + -3) = 0

Reorder the terms:
(3 + a)(-3 + a) = 0

Multiply (3 + a) * (-3 + a)
(3(-3 + a) + a(-3 + a)) = 0
((-3 * 3 + a * 3) + a(-3 + a)) = 0
((-9 + 3a) + a(-3 + a)) = 0
(-9 + 3a + (-3 * a + a * a)) = 0
(-9 + 3a + (-3a + a2)) = 0

Combine like terms: 3a + -3a = 0
(-9 + 0 + a2) = 0
(-9 + a2) = 0

Solving
-9 + a2 = 0

Solving for variable 'a'.

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

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

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

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

Simplifying
a2 = 9

Take the square root of each side:
a = {-3, 3}