1. Use the Mean Value Theorem to prove the following inequalities(a) sin x < x for x > 0(b) tan x > x for 0 < x < π22. Use the MVT to prove the inequality | sin a − sin b| ≤ |a − b| for all aand b.3. Show that √1 + x < 1 + 12 xif x > 0.
Question
- Use the Mean Value Theorem to prove the following inequalities(a) sin x < x for x > 0(b) tan x > x for 0 < x < π22. Use the MVT to prove the inequality | sin a − sin b| ≤ |a − b| for all aand b.3. Show that √1 + x < 1 + 12 xif x > 0.
Solution
-
(a) According to the Mean Value Theorem, there exists a number c in (0, x) such that cos(c) = (sin(x) - sin(0)) / (x - 0). Since 0 < cos(c) <= 1 for 0 < c < x, we have sin(x) / x <= 1. Since sin(x) is positive for x > 0, we have sin(x) < x.
(b) Similarly, there exists a number c in (0, x) such that sec^2(c) = (tan(x) - tan(0)) / (x - 0). Since sec^2(c) > 1 for 0 < c < π/2, we have tan(x) / x > 1. Since tan(x) is positive for 0 < x < π/2, we have tan(x) > x.
-
According to the Mean Value Theorem, there exists a number c between a and b such that cos(c) = (sin(a) - sin(b)) / (a - b). Since -1 <= cos(c) <= 1, we have |sin(a) - sin(b)| <= |a - b|.
-
Let f(x) = √1 + x - 1 - x/2. Then f'(x) = 1/(2√1 + x) - 1/2. Since f'(x) < 0 for x > 0, f(x) is decreasing for x > 0. Since f(0) = 0, we have f(x) < 0 for x > 0, which means √1 + x < 1 + x/2 for x > 0.
Similar Questions
Prove thatcos x ≥ 1 − 12x2 and sin x ≥ x − 12x3 for all x ∈ [0, π/2].Hint: Use the mean value theorem
If 𝑓(𝑥) = 𝑠𝑖𝑛−1𝑥, 0 < 𝑎 < 𝑏 < 1, use Mean value theorem to prove that𝑏 − 𝑎√1 − 𝑎2 < 𝑠𝑖𝑛−1𝑏 − 𝑠𝑖𝑛−1𝑎 < 𝑏 − 𝑎√1 − 𝑏2
Show that the following functions are differentiable at x = 0.(a) |x| sin x (b) x2/3 sin x (c) 3√x(1−cos x) (d) h(x) ={x2 sin(1/x), x 6 = 00, x = 0.Page 3
Let 0 < a < b and f : [a, b] → R be continuous on [a, b]. Prove that there exists c ∈ [a, b] suchthatZ batf (t)dt = 12 f (c)(b2 − a2).Hint) Consider the functionh(x) = 12 f (x)(b2 − a2) −Z batf (t)dt.Use the comparison principle and the intermediate value theorem
10. Let 0 < a < b and f : [a, b] → R be continuous on [a, b]. Prove that there exists c ∈ [a, b] suchthatZ batf (t)dt = 12 f (c)(b2 − a2).Hint) Consider the functionh(x) = 12 f (x)(b2 − a2) −Z batf (t)dt
Upgrade your grade with Knowee
Get personalized homework help. Review tough concepts in more detail, or go deeper into your topic by exploring other relevant questions.