Thread: Please Help!

hi, i have a chart, at 0.25, the value is 1/64
at 0.5, the value is 1/16
at 0.75 the value is 9/64
at 1, the value is 1

how can this information be written in summation notation?

Originally Posted by samantha_malone

hi, i have a chart, at 0.25, the value is 1/64
at 0.5, the value is 1/16
at 0.75 the value is 9/64
at 1, the value is 1

how can this information be written in summation notation?

1/4 => 1^2/4^3
2/4 => 2^2/4^3
3/4 => 3^2/4^3
4/4 => 4^2/4^3

so i guess sum(i=1,4)(i^2/64), except that i fail to see where any sums are taken? it is just a series...

well what if i gave the following information instead:

0.2 = 0.008
0.6 = 0.144
0.8 = 0.128
1 = 1

how would i write that in summation notation?

are these functions? or measurements of some kind? i dont think i can help you without more context.

Originally Posted by xifentoozlerix

are these functions? or measurements of some kind? i dont think i can help you without more context.

well basically, i was to pick points on a graph and then check their heights at that point and then find the area of a rectangle formed with the width and the height. these values represent the x values and then the area, and my assignment is to rewrite that info in summation notation.

I have no clue how to go about that problem. Are the areas being summed? If so, I get the impression that you are approximating the area under a curve using rectangles (presumably to eventually derive the integral from a Reimann sum). I think that is way off base though. Sorry.

I suspect this assignment has been given in preparation for learning how to integrate and that you are supposed to use the sum of the areas of these rectangles as an approximation for the area under the curve.

Summation notation is not exceedingly useful if you do not have an equation for the curve. You could however refer to your heights as , etc, in which case you could make use of summation notation for the sum of the areas as follows (using your first set of data).