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Using the result from the previous page we get

Now if

then

Now since

we get

or

and thus

This gives us

So

Then we have

Together this gives us

So what sign to use? If we look at the original function between 1 and 2 we have an increasing function starting at 0 and ending at

So the integral from 1 to 2 should be positive and less than the above. But our integral is

We must thus have

A graph of this (but whit the slight change of adding an absolute function to include the negative *x*-values) is seen below.

Generalizing a bit we get

Here the first leading *a* comes from the 1/1/*a* we get as we integrate over a linear inner function, and we then need to divide by the *x*-coefficient (the gradient of the liner term *x*/*a*). Then it is “just” a bunch of algebra (it took me three trials to get all the *a*´s right).

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