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Mathematics 15 Online
OpenStudy (trisarahtops):

Calculus Question!! Medal!!

OpenStudy (trisarahtops):

OpenStudy (trisarahtops):

@rebeccaxhawaii

OpenStudy (jdoe0001):

dunno that one myself

OpenStudy (bmk614):

The integral is the same at the area under the curve. So given the integral from -2 to 2, the width of each of the 4 rectangles are \[\frac{ 2-(-2) }{ 4 }=1\] Since this is a midpoint sum, you need to to find the midway point of each rectangle, which would be at the .5 mark. You plug in each x-point, which are -1.5,-0.5,0.5, 1.5, to find their respective y values. To find the area of each rectangle you multiply the width (1) by the height (y). You then add all the rectangles together to get your Mid-point sum.

OpenStudy (trisarahtops):

Ohhh wow I understand now.

OpenStudy (trisarahtops):

ok so where do I plug in -1.5,-0.5,0.5, 1.5

OpenStudy (bmk614):

Into the equation x^3 +8

OpenStudy (trisarahtops):

and then I solve that and multiply it by 1 and then add them all up?

OpenStudy (bmk614):

Yes! It is just 1, because that just so happens to be the width. Normally you would multiply it by some other number.

OpenStudy (trisarahtops):

So do i plug them in to just x^3+8 or the whole \[\int\limits_{-2}^{2} (x^3 +8) dx\]

OpenStudy (bmk614):

Just x^3+8 because the integral is just the equation for finding the area under the curve.

OpenStudy (trisarahtops):

ok let me do that. i can't message you when I've done it if you want?

OpenStudy (bmk614):

Yeah! I would love to see what you get!

OpenStudy (trisarahtops):

ok cool i'm almost done

OpenStudy (trisarahtops):

I got about 32.015

OpenStudy (bmk614):

I got exactly 32

OpenStudy (bmk614):

\[[1*[(-1.5)^3+8]] +[1*[(.5)^3+8]]+[1*[(.5)^3+8]]+[1*[(1.5)^3+8]]\]

OpenStudy (bmk614):

The first .5 should be negative.

OpenStudy (trisarahtops):

that's exactly what i did. I guess using the rectangle method is never exactly accurate. Anyway is 32 the final answer?

OpenStudy (bmk614):

Yes. I did that and got exactly 32.

OpenStudy (trisarahtops):

That fine I agree I just wanted to know if there are any more steps or if 32 is the final answer?

OpenStudy (bmk614):

I just meant it was the final answer.

OpenStudy (trisarahtops):

oh okay. Thanks for the help :)

OpenStudy (bmk614):

No problem!

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