11-29-2008, 03:59 PM
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I downloaded a program called SIGMA to my TI-84. It's kind of clunky because you have to press [enter] as many times as you have terms in the sequence. It's okay if you have like 4 or 5 terms or so. -----Added 11/29/2008 at 03:59:29 EST-----
Using the TI-84, I followed the suggestion below; although I found that when I did SEQ first and then SUM I had to do SUM(2nd ANS) and that worked fine. I like it because I can compute the sum of the series in the second step rather than having to keep track of how many times I press [enter]. I like the "nested function" version even better that does it in one step, e.g. sum(seq(x^2,x,1,100)). Thank you jwithnell's husband! Quote:
Originally Posted by jwithnell  Hi,
I'm jwithnell's husband -- I'm a math teacher, and the ti-83 has a couple of functions that will allow you to do what you are asking.
The first is seq() and the other is sum(). You get to both through the 2nd LIST button: seq() through 2nd LIST OPS, sum through 2nd LIST MATH.
The seq function takes an expression, then a variable to increment, the start value, the end value and then an optional step size. What it generates is a list of values of the expression. So seq(x^2, x, 1, 100, 1) would generate the values 1, 4, 9, 16, ... 10000.
The second function, sum(), will then add the values in a list, so it becomes very easy to do the sigma through the two functions.
sum(seq(x^2,x,1,100))
which will then produce the final answer you want 338350. Of course for that particular series, there is a formula ... but I leave that as an exercise for the student! (hint: it is a cubic function) |
Last edited by jaybird0827; 12-01-2008 at 08:05 PM.
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