Definite Integration Question 37

Question: The value of $ \int _{0}^{1}{|3x^{2}-1|dx} $ is

[AMU 1999]

Options:

A) 0

B) $ 4/3\sqrt{3} $

C) 3/7

D) 5/6

Show Answer

Answer:

Correct Answer: B

Solution:

$ \int _{0}^{1}{|3x^{2}-1|dx=\int _{0}^{1/\sqrt{3}}{(1-3x^{2})dx+\int _{1/\sqrt{3}}^{1}{(3x^{2}-1)dx}}} $

$ =[x-x^{3}]_0^{1/\sqrt{3}}+[x^{3}-x] _{1/\sqrt{3}}^{1} $

$ =\frac{1}{\sqrt{3}}-\frac{1}{3\sqrt{3}}+\frac{-1}{3\sqrt{3}}+\frac{1}{\sqrt{3}} $

$ =\frac{4}{3\sqrt{3}} $ .