In Exercises 139–142, find the length of each curve.
139. y = (1/2)(e^x + e^(−x)) from x = 0 to x = 1.

Find the limits in Exercises 13–20. (If in doubt, look at the function’s graph.)

13. lim(x → 1⁻)arcsin(x)

Evaluate the integrals in Exercises 77–90.

84. ∫(from 2 to 4)2dx/(x²-6x+10)

143.

b. Find the average value of ln(x) over [1, e].

In Exercises 1–6, use l’Hôpital’s Rule to evaluate the limit. Then evaluate the limit using a method studied in Chapter 2.

5. lim (x → 0) (1 - cos x) / x²

Use l’Hôpital’s rule to find the limits in Exercises 7–52.

49. lim (x → 0) (x - sin x) / (x tan x)

Use l’Hôpital’s rule to find the limits in Exercises 7–52.

12. lim (x → ∞) (x - 8x²) / (12x² + 5x)