Definite Integration Question 67

Question: The value of $ \int _{0}^{\sqrt{2}}{[x^{2}]dx}, $ where [.] is the greatest integer function

[AIEEE 2002]

Options:

A) $ 2-\sqrt{2} $

B) $ 2+\sqrt{2} $

C) $ \sqrt{2}-1 $

D) $ \sqrt{2}-2 $

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Answer:

Correct Answer: C

Solution:

$ I=\int_0^{\sqrt{2}}{[x^{2}]dx} $

$ =\int _{0}^{1}{[x^{2}]dx+}\int _{1}^{\sqrt{2}}{[x^{2}]dx} $

$ =\int _{0}^{1}{0dx+}\int _{1}^{\sqrt{2}}{dx} $

$ =[x]_1^{\sqrt{2}}=\sqrt{2}-1 $ .