# Calculator Techniques for Solving Progression Problems

Franz Mesa I have a problem in geometric progression, i got a math error because the value of my r is negative. Here is the example

Find the sum of the first 7 terms of the sequence 9, -6, 4,...

Jhun Vert Mode 3 6 is not applicable for negative common ratio. You can use it though but you need to exclude the sign and get your actual sign manually. This approach however is not applicable for for finding the sum of GP.

Bryan Baring

thank you much

WhatTheFarl thank you very much sir! sobrang laking tulong po. Godbless!

Shiena Dale Nazareno Sir, how about the technique when the given is SUM or when the problem requires to find the sum of odd numbers of the series?

Vanessa Malenab... In harmonic Progression, do I need to reciprocate the given when I input it on the calculator?

Example:
What is the 13th term of a harmonic sequence whose 3rd term is 12 and 8th term is 2?
A. 12/11
B. 11/10
C. 10/9
D. 9/8

SOLUTION:
Set calculator to MODE 3-2. Get the reciprocals of the given.

Encode:
x y
3 1/12
8 1/2

Press AC key.

Enter: 13ŷ
Result: 11/12

Get the reciprocal of the result. Therefore, the answer is A. 12/11.

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