Cal 1 Limits Question: as x->0 ?

I don't understand how evaluate this! Please explain :)

lim x->0 (cot(5x)) / (cot(7x))

10 pts best answer

Thanks!!

Update:

**sorry i should have specified! without derivatives please, we haven't covered them yet!

1 Answer

Relevance
  • Melvyn
    Lv 7
    8 years ago

    cos[5x] / Sin[5x] * Sin [7x]/Cos[7x] = (cos5x sin[7x]) /( sin[5x] cos[7x])

    this is obviously 0/0 when x=0 so use L'Hospitals rule

    (7Cos[5x]Cos[7x]-5Sin[5x]sin[7x])/(5cos [5x]cos[7x]-7sin[5x]sin [7x])

    evaluated at x=0 ,7 / 5 = 1.4

Still have questions? Get your answers by asking now.