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Question

Question: \(\int _ { 0 } ^ { \infty }\)[2 e<sup>-x</sup>] dx, where [.] denotes the greatest integer function,...

0\int _ { 0 } ^ { \infty }[2 e-x] dx, where [.] denotes the greatest integer function, is equal to

A

0

B

ln 2

C

e2

D

2e–1

Answer

ln 2

Explanation

Solution

Since 0 < 2 e-x ≤ 2 ∀ x ∈ [0, ∞), [2 e-x] = 0, for x > ln2.

Hence the given integral = 0ln2dx\int _ { 0 } ^ { \ln 2 } d x + 0 = ln 2