300 Followers Problem

Calculus Level 3

The Value of the integral

1 3 \displaystyle\int_{-1}^{3} ( x + x 1 ) (|x|+|x-1|) d x dx



The answer is 9.

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3 solutions

I don't think this is a level 5 problem, just done it by area under curve

You're right-this is an easy (very easy) calculus problem. It should be Level 2.

bobby jim - 6 years, 5 months ago
Prakhar Gupta
Jan 12, 2015

This can also be done by breaking the limits of integrals so that we can remove the modulus sign. The given integral is:- 1 3 ( x + x 1 ) d x \int_{-1}^{3} (|x|+|x-1|) dx This can be broken into 3 3 parts as follows:- = 1 0 ( x + 1 x ) d x + 0 1 ( x + 1 x ) d x + 1 3 ( x + x 1 ) d x =\int_{-1}^{0}(-x+1-x) dx + \int_{0}^{1}(x+1-x) dx + \int_{1}^{3} (x+x-1) dx Now we have removed the modulus sign and we can integrate it easily and get the answer 9 9 .

Masbahul Islam
Dec 31, 2014

The area under the curve is 9

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