Definite Integration Question 463

Question: $ \int_0^{1.5}{[x^{2}]dx} $ , where $ [.] $ denotes the greatest integer function, equals

[IIT 1988; DCE 2000, 01]

Options:

A) $ 2+\sqrt{2} $

B) $ 2-\sqrt{2} $

C) $ -2+\sqrt{2} $

D) $ -2-\sqrt{2} $

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Answer:

Correct Answer: B

Solution:

$ \int_0^{1.5}{[x^{2}]dx=\int_0^{1}{[x^{2}]dx+\int_1^{\sqrt{2}}{[x^{2}]dx+\int _{\sqrt{2}}^{1.5}{[x^{2}]dx}}}} $

$ =0+\int_1^{\sqrt{2}}{1dx+\int _{\sqrt{2}}^{1.5}{2dx=\sqrt{2}-1+3-2\sqrt{2}=2-\sqrt{2}}} $ .