- #1
mr_coffee
- 1,629
- 1
Hello everyone.
I'm studying for my exam and I'm reveiwing some problems but this one isn't making sense to me:
11^9(9 choose 0) - 11^8(9 choose 1) + 11^7(9 choose 2) - ... - 11^2(9 choose 7) + 11^1 (9 choose 8) - 11^0 (9 choose 9)
answer:
(11-1)^9 = 10^9 = 1,000,000,000.
work looked like:
(9 choose 0) 11^9 (-1)^0 + (9 choose 1)11^8(-1)^1
Can someone explain to me how they did this?
I see the 11 is decreasing, and the signs are alternating, it looks like a binomial expansion but I'm not seeing how they simplified that.
Thanks
I'm studying for my exam and I'm reveiwing some problems but this one isn't making sense to me:
11^9(9 choose 0) - 11^8(9 choose 1) + 11^7(9 choose 2) - ... - 11^2(9 choose 7) + 11^1 (9 choose 8) - 11^0 (9 choose 9)
answer:
(11-1)^9 = 10^9 = 1,000,000,000.
work looked like:
(9 choose 0) 11^9 (-1)^0 + (9 choose 1)11^8(-1)^1
Can someone explain to me how they did this?
I see the 11 is decreasing, and the signs are alternating, it looks like a binomial expansion but I'm not seeing how they simplified that.
Thanks