Number of integral terms in the expansion of \7 ( 12 )+11 ( 16 ) \824 is equal to .
Answer
138
Solution
Tr+1=824Cr 7 824-r2 11 r6
Integral r6 and 824-r2 are integers r is a multiple of 6 (then r is even too)
r=0, 6, 12, , 822 (0 r 824)
Number of terms = 8226+1=138
Answer: 138