geometric sequence problems
Find the number of terms in the sequence
512, -256 , 128 , ......, -1
I got the first one correct, but i'm not sure if complete the question in proper steps due to my mistake in question two.
tn= ar^n-1
-1=512(-1/2)^n-1
-1/512=(-1/2)^n-1
-2^-9 = -2^1-n
-9= 1-n
-10= -n
10=n
There is 10 terms in total.
Find the last term of the sequences
the problem came out after i misdo with signs
1/384, -1/192, 1/96, ......., -16/3
-16/3=1/382(-1/2)^n-1
-16x382/3=(-1/2)^n-1
-2048= -2^1-n
-2^11= -2^1-n
11=1-n
10=-n
-10=n
but the answer is 12 ^^;;
i believe i made an mistake at -2048= -2^1-n..."factoring?" the -2048(negative exponents? stuck). Please check if my first problem is completed in proper steps or not. Thankyou~(Wondering)
