Computing series in MATLAB

2015 3 7
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更新时间：2015 3 8
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Hello!
I wonder if it is possible somehow to force MATLAB to compute ANY series for this function: ((4+3x)/(x+2))^(2x-1) as x->inf. I need to find the limit without using the limit function in MATLAB.
I tried some ways, but they don't appear to be working as MATLAB says there is an error.
I would be very thankful for your help!

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Rick Rosson
Rick Rosson 2015-3-7
Please post your code and the exact error message.
Svetlana
Svetlana 2015-3-7
Firstly, I tried to compute a Taylor series so I've made a substitution: t = 1/x, t->0
g = ((3/t + 4)/(1/t + 2))^(2/t - 1)
taylor(g)
Warning: Cannot compute a Taylor expansion of '((3/t + 4)/(1/t + 2))^(2/t - 1)'. Try 'series' with the 'Left', 'Right', or 'Real' option for a more general expansion. [taylor]
or:
f = ((3/t + 4)/(1/t + 2))^(2/t - 1)
series(f, t = 0, Left)
Error: The expression to the left of the equals sign is not a valid target for an assignment.

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Roger Stafford
Roger Stafford 2015-3-8
编辑：Roger Stafford 2015-3-8

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The reason you're having trouble finding that limit is that there is no finite limit! The expression goes quickly to infinity as x approaches infinity. For the same reason the expression
((3/t + 4)/(1/t + 2))^(2/t - 1)
has no Taylor series because it has a singularity at t = 0. It approaches infinity from the right and zero from the left.

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