
With this definite integral, we can find its antiderivative and find the area.

Let's take a look at the graph...

Solving problems like this are not always this easy as this one. We can't always find the exact value of the definite integral.
Take a look at this problem and its graph.


We could use Riemann sums to find the area under the curve.


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These are the differentiation and integration formulas. We use these to help us determine the problems below.


Determine:
1)

u= x 3
du= 3x2
1/3du= x2 dx
If your wondering why u = x3 its because
(x3)2 = x6. So u is u2. We are trying to make the original function look like d/dx Arctan(x) integration formula.
Substitute ....................................................Resubstitute


You don't need " + C " in the intermediate steps because the C are not the same while your substituting.


(There's supposed to be an equal (=) sign in between the pictures)
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2)

So we do this,
6x-x2 -8 Factor out the negative.
-[(x2 -6x+8 +1) -1]
-[(x2 -6x+9) -1]
-[(x-3)2 -1]
1 - (x-3)2 We can replace this into the integral.

Let u = x+3
du = dx

Then RE-substitute..

And we're done
Homework: finish up arctrig exercises (7.5)
Wednesday's scribe will be Katrin.
Hi Ashlynn,
ReplyDeleteI have a question about #1 if you don't mind. You said:
u= x 3
du= 3x2
1/3du= x2 dx
but your integral has only xdx. Is it a typo or am I not seeing something obvious? Thanks,
e
Yes that is a typo. Thank you for telling me.
ReplyDeleteThe picture was supposed to read X squared.