Expand (x - 5)^2
(x - 5)^2 = (x - 5)(x - 5)
Multiply all the terms in the first parenthesis to all the terms in the 2nd:
x * x = x^2
x * -5 = -5x
-5 * x = -5x
-5 * -5 = 25
So we have:
x^2 - 5x - 5x + 25
Combine like terms:
x^2 - 10x + 25
Plug it back in:
y = (x - 5)^2 - 2
y = x^2 - 10x + 25 - 2
Combine like terms:
y = x^2 - 10x + 23
