Problem: If f(a)=a−2f(a)=a-2f(a)=a−2 and F(a,b)=b2+aF(a, b)=b^{2}+aF(a,b)=b2+a, then F[3,f(4)]F[3, f(4)]F[3,f(4)] is:
Answer Choices:
A. a2−4a+7a^{2}-4 a+7a2−4a+7
B. 282828
C. 777
D. 888
E. 111111 Solution:
F[3,f(4)]F[3, f(4)]F[3,f(4)] means the value of b2+ab^{2}+ab2+a when a=3a=3a=3 and b=2b=2b=2, namely, 777.