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# Definite Integral best method to double check answers?

A problem I am dealing with is finding the Definite Integral, from 1 to 2, of (4x^3 – 3x^2) dx:

I understand that you integrate, Plug in upper limit then subtract lower limit. my answer comes out to f(x) dx = 8 is this correct?

### 2 Answers by Expert Tutors

David U. | Dave the Math TutorDave the Math Tutor
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The number 8 is the correct number, and so is the process you described for how you got it.  However, what the 8 represents is not f(x)dx, but what you stated in your question, namely, the definite integral from 1 to 2 of (4x3 - 3x2).  So if you answered the question by saying "f(x)dx = 8", you could very well be marked wrong.  Labels are important!  You not only want to get something, you want to know what it is that you've got.

Maurizio T. | Statistics Ph.D and CFA charterholder with a true passion to teach.Statistics Ph.D and CFA charterholder wi...
5.0 5.0 (328 lesson ratings) (328)
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