(n+9) times (n+9)
FOIL n^2 +9n + 9n + 81 Do not forget the middle the O and the I
(r-11) times (r-11)
r^2 - 11r - 11r + 121
Can you guess why the third one is different? The positive and negative terms get rid of each other.
(n+9)^2
n^2+81
(r-11)^2
r^2-22
(z+13)(z-13)
Z^2
2 answers
14