I will assume you meant:
∞ Σn=1 -4(-1/2)^(n-1)
= -4(-1/2)^0 + -4(-1/2)^1 + -4(-1/2)^2 + -4(-1/2)^3 + ...
= -4(1) + 4(1/2) - 4(1/4) + 4(1/8) ...
looks like a GS, with a = -4, r = -1/2)
sum(∞) = a/(1-r) = -4/(1 + 1/2)
= -4/(3/2)
= -4(2/3)
= -8/3 <---- acceptable answer
= -2 2/3 <---- acceptable answer
you had that, you are correct
Homework help!!
∞ Σn=1 -4(-1/2)^n-1
This converges at -2 2/3, or -2.66– Correct? The formula I used is a1/1-r. then i put -4/(3/2). then multipled by reciprocal. to get -8/3. then -2 2/3. and then to -2.66-
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