Here's the question you clicked on:
liliy
find the value of the sum: summation j=0 until j=8; (1+(-1)^j))
\[\sum_{0}^{8} (1+(-1)^j)\]
we need to use the formula for progresion. but i dont know how. bec the formula is : n(a sub 1 +a sub n) /2
but is the zero considered ":a sub 1 or a sub 0,?"
Idk why you need a formula... unless I'm missing something.. You should be able to just plug in and get your answer...
the instructions say use th formla
n should be 8, but not too sure about a, maybe the current #? I haven't done this in awhile :P.
wait, without the formula the answer is 10?
hmm so this formula is not giving me that answer. no matter which numbers i put in.