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?

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?

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^{3} - 3x^{2}). 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.

Yes, your answer is correct.

You compute first the indefinite integral, F(x), for your function, f(x) = 4x^{3} -3x^{2}.

In this case you get **F(x) = ∫ (4x ^{3}-3x^{2}) dx = 4x^{4}/4 -3x^{3}/3+ c = x^{4 }- x^{3} + c.**

*(You can verify that this is the right indefinite integral by computing the first derivative).*

Now, you have to calculate **F(2)-F(1) = 2 ^{4}-2^{3}+c -(1^{4}-1^{3}+c) = 16-8+c -(1-1+c) = 8 i.e.,
**you have shown that