Question 307140
{{{(N-3)^2 = (N-3)*(N-3)}}}
Use FOIL to multiply the terms through.
(FOIL = first, outer, inner last)
{{{(N-3)*(N-3) = (N*N) + (-3*N) +  (-3*N) + (-3*-3)}}}
Simplify
{{{N^2 - 3N - 3N + 9}}}
Combine like terms
{{{N^2 - 6N + 9}}}