Problems involving limits in calculus

[Angeline Ling]

Homework Statement

lim [(5^(n+1))+(7^(n+1))]/(5^n-7^n) as x→infinity
lim [sec x - tan x] as x → ∏/2

 

[HallsofIvy]

Sigh. So you did not read the introductory material nor look at very many posts here. If you had, you would have realized: "This is perhaps the most common mistake that new members make. When posting homework, if you do not make any attempt yourself, then other people are not allowed to help at all! This holds particularly true in the homework forums!"