## MarcLeclair 2 years ago Use l'hopsital RUle to solve for lim x-->Pi / 4 5(1-tanx)secx. I solve for the equation (by plugging in pi/4) and I don't get zero, however, my answer is still wrong, should I still use the hospital rule?

1. tkhunny

$$\tan\left(\dfrac{\pi}{4}\right) = 1$$ $$\sec\left(\dfrac{\pi}{4}\right) = \sqrt{2}$$ 1) Never "plug in". Sometimes substitution is approprate. 2) This is not an indeterminate form. Please don't use l'Hopital's Rule. 3) Please supply the ENTIRE problem statement.

2. MarcLeclair

That is the entire problem. and I should've calculated in radian... right?

3. tkhunny

You can calculate in Light Years if you like. It's NOT an indeterminate form.

4. tkhunny

That doesn't mean we can't find the limit. We just can't use (or don't need) l'Hopital's Rule.