Doug C. answered 07/06/23
Math Tutor with Reputation to make difficult concepts understandable
To get the limit using a table of values you would have to do something like this:
desmos.com/calculator/eytnrnglpn
Not sure if you have learned L'Hospital's rule yet? But if so you can calculate the limit manually.
sin(7x)/tan(2x) as x->0 is an indeterminate form so the "rule" can be applied (taking the derivative of the numerator divided by the derivative of the denominator gives a function that will have the same limit as the original:
7cos(7x)/2sec2(x) has a limit that looks like this (as x goes to 0):
7(1) / 2(1) = 7/2 (which is the same value that the table values are approaching in the Desmos graph).
Seung hyun H.
Thank you for your kind reply. It helps me to solve the problem.07/07/23
Doug C.
You can also try the fact that the lim as x goes to 0 of sin(x)/x = 1. rewrite as sin(7x)cos(2x)/sin(2x), then introduce 7x in numerator and denominator: 7x sin(7x)cos(2x)/7x sin(2x) The sin(7x)/7x has a limit of 1 as x goes to 0. Now you have: 7xcos(2x) / sin(2x) rewrite sin(2x) as 2 sinx cosx 7xcos(2x)/ 2 sin(x) cos(x) (the limit of x /sinx is 1, so the factors that remain: 7cos(2x)/2cos(x) and the limit as x goes to 0 gives: 7(1) / 2(1).07/06/23