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Mathematics 13 Online
OpenStudy (anonymous):

Calculate the area of the shaded rectangles in Figure 18. Which approximation do these rectangles represent?

OpenStudy (anonymous):

OpenStudy (thefurball):

The area of a rectangle is just base times height. Just add all of their areas. The type of approximation depends on where the top of each rectangle hits the curve. If the curve is in the middle of the top of the rectangle, it's midpoint. If it's the right or left corner, it's right or left riemann sum

OpenStudy (thefurball):

you can find the height by plugging in the corresponding x value

OpenStudy (anonymous):

so what do you get?

OpenStudy (anonymous):

is it midpoint?

OpenStudy (thefurball):

Yes it is midpoint.

OpenStudy (anonymous):

so can you guide me through how to solve it using that method?

OpenStudy (thefurball):

I'll walk you through the first rectangle. You need to find base times height. The base is easy, it's just the distance from -3 to -2, which is 1. The height is what you get when you plug the x value -1 into the equation. For that, you get y(-1) = 4 + 1 / 1+1 = 5/2 so the area is 1 * 5/2 = 5/2. Do that for all rectangles and add all of the areas

OpenStudy (thefurball):

dang did it wrong hold on the x value isnt -1

OpenStudy (thefurball):

the x value you plug into the equation should be -2.5

OpenStudy (anonymous):

dont ujust do the midpoint equation with F(n)+f(n+1)/2

OpenStudy (anonymous):

confused

OpenStudy (anonymous):

or do we not approximate?

OpenStudy (anonymous):

can you just do it for me haha.

OpenStudy (thefurball):

this method is a way to find the approximate area under the curve

OpenStudy (thefurball):

so the answer will be 1 * (y(-2.5)+y(-1.5)+y(-.5)+y(.5)+y(1.5)+y(2.5)) just plug all those values into the equation

OpenStudy (anonymous):

why is it 2.5?

OpenStudy (thefurball):

For the first rectangle, the height will be y when you plug in halfway between -3 and -2, which is -2.5. If you plug -2.5 into the equation, you get the height of the rectangle.

OpenStudy (anonymous):

oh I gotcha

OpenStudy (anonymous):

What solution did you end up getting?

OpenStudy (anonymous):

?

OpenStudy (thefurball):

for the first rectangle or all of them?

OpenStudy (anonymous):

all of them

OpenStudy (anonymous):

?

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