Calculus question on lower sums

[85 Cutlass Brougham]

Yes, it is take home test time again. I figured out all the other questions, but I am wondering about this one. It asks for the lower sum of f(x)=25-x^2, over the interval (0,5), bounded by the X axis at the bottom and the Y axis at one side with f(x) being the other border. using 5 equal rectangles. To me, this means the rectangles are of width one and height equals the Y value at the given x value, as these would be inscribed rectangles under the curve. So, I added up the Y values from X=1 to X=5 and used that as my answer, 70 square units. Am I right? Is it really that easy? I have to turn it in tomorrow, but hopefully someone who understands this can post to it before class.

 

[85GPLef41]

uuuuuuummmmmm :shock: I suck at math but it sounds right jk i wouldn't have a clue. Hope you get it right :lol:

 

[patmckinneyracing]

I'm hoping your in AB calculus cause I haven't been introduced to BC Calculus yet. It sounds like your finding the area of region that is bound, but it also sounds like your going over "cross sections" as well. By your description, your math is correct. My calculus teacher took up our TI-83 calculators so juniors could use them on the Texas finals. To check on the calculators, all you have to do is go to fInt after you hit the math button. Once you have the fInt highlighted, hit enter. From there, you type in the function as a function of x and then your limits. When its in the calculator it'll look like this:

fInt (25-x^2, x, 1, 5) (Once you have that typed in press enter)

Make sure you round off to the nearest thousandth in case it gives you a decimal.

We've been getting ready for the AP exams so I hope my evaluation of this question is right. It does seem a little easy but some of them are that way. At the same time, those rectangular cross sections could play a factory, but I don't have your homework in front of me. You spelled "Calculus" wrong too, just remember it's "CalCLUEless"

 

[85 Cutlass Brougham]

Ooops... My spell check doesn't always work on titles. I fixed it though...thanks for catching it before I looked stupid! LOL... Anyhow, she gave us the hint that we shouldn't make it harder than it is and that it is alright to just add up rectangles. I am thinking this is the problem she was referring to as there were no other ones asking directly for area. The class I am in is Calculus I, btw. This test was on Integrals, Reimann Sums, Sigma notation, etc. and this is the first time we covered this material with regards to integrals. I am probably going to miss the class tomorrow though because I just can't sleep. It is now 4am and I have to be up at 7:30am, and I have work at 5pm to midnight. So, I probably have to skip it even though I don't want to. Also, the way it comes out it is all easy numbers, no decimals or fractions. (one squared, 2 squared, etc.)