Question

\[\lim_{x \rightarrow 0} \frac{\cos7x-\cos9x}{\cos3x-\cos5x}\]

Answer 1

\[\lim_{x \rightarrow 0} \frac{\cos7x-\cos9x}{\cos3x-\cos5x}\]

Answer 2

I did it like this:
\[\lim_{x \rightarrow 0} \frac{\-\sin7x+\sin9x}{\-\sin3x+\sin5x}\]

Answer 3

that's a negative sign

Answer 4

@hartnn

Answer 5

how did u get sin!! ??

Answer 6

L Hospital

Answer 7

yes L Hospitals rule

Answer 8

divide numerator and denominator by x

Answer 9

then use sin x/x = 1

Answer 10

or u canalso use COS A-COS B formula and rewrite the entire question,

then you can see if it is still 0/0 form, if so, use L hospital

Answer 11

thanks!

Answer 12

i think you are better off using COS A-COS B , formula

Answer 13

okay,let me see

Answer 14

well that was easy with formula!!

Answer 15

glad it worked out

Answer 16

math is fun : )

Answer 17

yes!