Question

Write the summation to estimate the area under the curve y = 2x2 + 1 from x = 0 to x = 4 using 4 rectangles and left endpoints.

Answer 1

https://gyazo.com/10fefff1c824a71908fefa15fce74b76
It's A, right?
Just making sure I got the right answer, haven't don math in quite some time.

Answer 2

@dinamix

Answer 3

yup its great mate @Ephemera

Answer 4

I got it wrong :(

Answer 5

@dinamix this is once again why just giving answers can be bad, you don't know the answer is wrong that you gave...

Answer 6

@Ephemera would you like to learn how to do this?

Answer 7

lol @zzr0ck3r he tell me do that

Answer 8

Of course @zzr0ck3r

Answer 9

remember we don't start at the beginning of the interval, which here you chose 0.


If we put it into 4 parts, from 0 to 4, we would use the interval [0,1], [1,2], [2,3], and [3,4]. When we take the width of the first interval, we have 1, so we start at 1 not 0. So what is the right answer?

Answer 10

It would be D, right?

Answer 11

correct

Answer 12

remember last time, \(x_1=4.5\) not \(4\) even though we were on the interval \([4,6]\).

Answer 13

\[\sum_{i=1}^{4}(2i^2+1) = 3+9+19+33\] @Ephemera i think should be like that

Answer 14

So if it was for example 3 to 5, I'd divide it into 3,3.5,4,4.5?

Answer 15

once again, @dinamix just giving the answer would not help really, with logic and reasoning you can lead them to the correct answer.

Answer 16

@Ephemera yes, if they said 4 intervals

Answer 17

well no, it would be 3.5, 4, 4.5, 5

Answer 18

this is assuming they want right triangles, which is pretty normal

Answer 19

but the intervals would be [3,3.5], [3.5,4], [4,4.5], [4.5, 5]

Answer 20

Ok, think I got it
I reset my exam because I got a low grade on the last....can you check over my work @zzr0ck3r?

Answer 21

@zzr0ck3r wow u are good teacher i like u ;)

Answer 22

Just post questions as you have them, I am not sure how ethical that is...