101–104. Proving identities Prove the following identities.
cosh (x + y) = cosh x cosh y + sinh x sinh y
Briggs 3rd Edition
Ch. 7 - Logarithmic, Exponential Functions, and Hyperbolic Functions
Problem 7.1.19
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101–104. Proving identities Prove the following identities.
cosh (x + y) = cosh x cosh y + sinh x sinh y
Explain why or why not Determine whether the following statements are true and give an explanation or counterexample. Assume x > 0 and y > 0.
d. 2ˣ = 2² ˡⁿ ˣ
Geometric means A quantity grows exponentially according to y(t) = y₀eᵏᵗ. What is the relationship among m, n, and p such that y(p) = √(y(m)y(n))?
11–15. Identities Prove each identity using the definitions of the hyperbolic functions.
cosh 2x = cosh²x + sinh²x (Hint: Begin with the right side of the equation.)
Harmonic sum In Chapter 10, we will encounter the harmonic sum 1 + 1/2 + 1/3 + ⋯ + 1/n. Use a left Riemann sum to approximate ∫[1 to n+1] (dx/x) (with unit spacing between the grid points) to show that 1 + 1/2 + 1/3 + ⋯ + 1/n > ln(n + 1). Use this fact to conclude that lim (n → ∞) (1 + 1/2 + 1/3 + ⋯ + 1/n) does not exist.
63–68. Definite integrals Evaluate the following definite integrals. Use Theorem 7.7 to express your answer in terms of logarithms.
∫₁ᵉ^² dx/x√(ln²x + 1)