asked 103k views
0 votes
Use the Mean Value Theorem (MVT) to show that sqrt(y) - sqrt(x) < (y - x)/(2sqrt(x)) if 0 < x < y.

a) x < y/2
b) x > y/2
c) x < y
d) x > y

asked
User Jnelson
by
8.0k points

1 Answer

4 votes

Final answer:

Using the Mean Value Theorem, we've shown the required inequality for the function f(x) = sqrt(x) over the interval (x, y) when 0 < x < y, confirming that option c. x < y is correct.

Step-by-step explanation:

The question asks us to use the Mean Value Theorem (MVT) to show that sqrt(y) - sqrt(x) < (y - x)/(2sqrt(x)) for 0 < x < y.

The MVT states that if f(x) is a function that is continuous on the closed interval [a, b] and differentiable on the open interval (a, b), then there exists some c in (a, b) such that f'(c) = (f(b) - f(a)) / (b - a).

To apply the MVT to this problem, we'll consider f(x) = sqrt(x) which is continuous and differentiable on the interval (x, y) with y > x > 0.

Computing the derivative, we get f'(x) = 1/(2sqrt(x)). By the MVT, there exists a c between x and y such that

f'(c) = (f(y) - f(x)) / (y - x) = (sqrt(y) - sqrt(x)) / (y - x).

Hence, we have 1/(2sqrt(c)) = (sqrt(y) - sqrt(x)) / (y - x).

Because c > x, we know that sqrt(c) > sqrt(x), and hence 1/(2sqrt(c)) < 1/(2sqrt(x)).

Multiplying both sides by (y - x), we obtain the inequality sqrt(y) - sqrt(x) < (y - x)/(2sqrt(x)).

Option (c) x < y is the correct option for the final answer because it summarizes the interval condition under which the Mean Value Theorem was applied and the inequality was established.

answered
User Eugene Laminskiy
by
8.8k points
Welcome to Qamnty — a place to ask, share, and grow together. Join our community and get real answers from real people.