TI-84 Plus CE field manual for IB Math
9
All coursesSumming a sequence
Use the calculator's Σ command to add the terms of a sequence over a specified range.
Find n=1∑123(1.2)n−1.
1
Open the summation template: press (the F2 shortcut) to open the FUNC menu, then press for 2:summation Σ(.
2
Fill the template, moving between boxes with the arrow keys: type for the variable, for the lower limit, and for the upper limit. The expression box already opens with a parenthesis, so type , then press to step out of the exponent and to close that opening parenthesis. The dummy variable name does not change the value of the sum.
3
Press to evaluate.
n=1∑123(1.2)n−1≈119.
Your turn
Work each one on your calculator, then check the answer.
- 1
Find n=1∑184(1.15)n−1.
- 2
Find n=1∑105(0.8)n−1.
- 3
Find n=1∑20n(0.8)n.