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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

User Jnelson
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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.

User Eugene Laminskiy
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