[5] Compute each of the following limits or show that they do not exist: (a) [2.5| lim cos( 5x) - cos(7x ) (b) [2.5] A metal cable has radius r and...

compute each of the following limits or show that they do not exist

3. [5] Compute each of the following limits or show that they do not exist:(a) [2.5| limcos( 5x)- cos(7x )(b) [2.5] A metal cable has radius r and is covered by insulation. The velocity v of an electricalimpulse in the cable isU= -c( Rr) " In (Rr)where c and R are positive constants. Find lim v and interpret your answer.