If m and n are odd integers, how many terms in the expansion of $(m+n)^8$ are odd?
+118609 If m and n are odd integers, how many terms in the expansion of $(m+n)^8$ are odd?
an odd times an odd is odd so m^k is odd and n^(8-k) is odd so times them together and they are odd
But all the coefficients except for the 1 at each end are even. An even time an odd = even
So there are 9 terms in total and 7 of them will be even, the first and the last will be odd
