May 23, 2009 #1 wimma Messages 37 Reaction score 0 Homework Statement lim (x-> infinity) sinh(x)sinh(e^(-x)) Homework Equations None really. The Attempt at a Solution L'Hospital?
Homework Statement lim (x-> infinity) sinh(x)sinh(e^(-x)) Homework Equations None really. The Attempt at a Solution L'Hospital?
May 23, 2009 #2 Dick Science Advisor Homework Helper Messages 26,254 Reaction score 623 l'Hopital, yes. Try writing it as sinh(e^(-x))/(1/sinh(x)). Now the form is 0/0.
May 23, 2009 #3 wimma Messages 37 Reaction score 0 hmm.. still failing at this question. pls help further? I don't get a nice solution on applying lhospital
hmm.. still failing at this question. pls help further? I don't get a nice solution on applying lhospital
May 23, 2009 #4 Dick Science Advisor Homework Helper Messages 26,254 Reaction score 623 What did you get from l'Hopital?
May 23, 2009 #5 wimma Messages 37 Reaction score 0 i now get the limit to infinity of: e^(-x)cosh(e^(-x))/(cothxcosechx) considering substitution of y=f(x) then computing the limit for lny
i now get the limit to infinity of: e^(-x)cosh(e^(-x))/(cothxcosechx) considering substitution of y=f(x) then computing the limit for lny
May 23, 2009 #6 Dick Science Advisor Homework Helper Messages 26,254 Reaction score 623 That looks ok. Now look at the parts. What's lim coth(x)? What's lim cosh(e^(-x))?
May 23, 2009 #7 wimma Messages 37 Reaction score 0 cothx -> 1 cosechx -> 0 cosh(e^-x) -> 1 e^-x -> 0 i guess lhopital again...
May 23, 2009 #8 Dick Science Advisor Homework Helper Messages 26,254 Reaction score 623 Not so fast. Aside from the stuff that goes to 1, you've got e^(-x)*sinh(x). What's that? Use the definition of sinh.
Not so fast. Aside from the stuff that goes to 1, you've got e^(-x)*sinh(x). What's that? Use the definition of sinh.
May 23, 2009 #10 Dick Science Advisor Homework Helper Messages 26,254 Reaction score 623 Not so bad, huh?
May 23, 2009 #11 wimma Messages 37 Reaction score 0 Nope. Must be getting tired... it's like midnight here.
May 23, 2009 #12 wimma Messages 37 Reaction score 0 Also could u please verify that limit (x,y) -> (0,0) of (x^4*y^2)/(x^2 + y^2)2 is 0
May 23, 2009 #13 Dick Science Advisor Homework Helper Messages 26,254 Reaction score 623 Express the function in polar coordinates. Count powers of r.