How do I solve using A+bi form

(5-6i)^2
please show work!

(a - b)^2 = a^2 - 2ab + b^2
Let a = 5 and b = 6i
=> (5 - 6i)^2
= 5^2 - 2 * (5) * (6i) + (6i)^2
= 25 - 60i + 36i^2
= 25 - 60i - 36 ... [because i^2 = -1]
= - 11 - 60i
=> A = - 11 and b = - 60.

(5 - 6i)² = (5 - 6i)(5 - 6i)
. . . . . . = 25 - 30i - 30i + 36i²
. . . . . . = 25 - 60i - 36
. . . . . . = -11 + 60i

(5-6i) (5-6i)
=25 - 30i - 30i - 36 (i^2 = -1)
= -11 - 60i