I need to find which of these equations is a convergent series
OpenStudy (alones.):
Hrmm Im not actually sure :#
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jimthompson5910 (jim_thompson5910):
each series is a geometric series. Hopefully you agree with that statement and see why?
jimthompson5910 (jim_thompson5910):
sorry C isn't geometric
OpenStudy (adryin):
Isnt C arithmetic?
jimthompson5910 (jim_thompson5910):
yes it is, my bad
OpenStudy (adryin):
I need to find which one of these is a convergent series.
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jimthompson5910 (jim_thompson5910):
the three trailing dots imply that the series goes on forever
OpenStudy (adryin):
I know
jimthompson5910 (jim_thompson5910):
with geometric series, the infinite series only converges if and only if |r| < 1
OpenStudy (adryin):
Yes but the ratio for all of them except a have a ratio greater then 1 for me
jimthompson5910 (jim_thompson5910):
for example, B will not converge because r = 3 in this case and r = 3 makes |r| < 1 false
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jimthompson5910 (jim_thompson5910):
B will keep growing and growing. The sum won't converge to a fixed number
OpenStudy (adryin):
Thats what I'm thinking for all the equations
OpenStudy (adryin):
for c d= -0.5 and arithmetics go on forever
jimthompson5910 (jim_thompson5910):
what is the value of r for choice A?
OpenStudy (adryin):
r = \[-\sqrt{2}\]
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OpenStudy (adryin):
I think thats convergent but not sure
jimthompson5910 (jim_thompson5910):
correct r value, but it doesn't converge since r = -sqrt(2) = -1.414 approx
r = -1.414 makes |r| < 1 false
ie, r = -1.414 is more than 1 unit away from 0 on the number line
jimthompson5910 (jim_thompson5910):
A will grow forever just like B does, just at a slower pace
OpenStudy (adryin):
None of these equations converge then?
jimthompson5910 (jim_thompson5910):
what's the r value for E ?
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OpenStudy (adryin):
r = 2
jimthompson5910 (jim_thompson5910):
so E diverges
jimthompson5910 (jim_thompson5910):
what's the r value of D ?
OpenStudy (adryin):
d = -12
OpenStudy (adryin):
Wait...
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jimthompson5910 (jim_thompson5910):
no it's not arithmetic
OpenStudy (adryin):
I was thinking that
OpenStudy (adryin):
OH.... r = 3/4 so it is convergent
jimthompson5910 (jim_thompson5910):
yep r = 0.75 makes |r| < 1 true
since it's between r = -1 and r = 1
OpenStudy (adryin):
Thank you so much!
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