Math homework help: 1st 3 terms of seq. are "7, 14, 21"; find 42nd term

[jerrylinxdd]

The first three terms of a sequence are given. Round to the nearest thousandth (if necessary).
7, 14,21,..
{Find the 42nd term.}Find the 42nd term.

 

[Dr.Peterson]

The first three terms of a sequence are given. Round to the nearest thousandth (if necessary).
7, 14,21,..
Find the 42nd term.

You haven't shown any work, or told us what background you have. This question could be asked at several very different levels; you might be learning about arithmetic sequences and have a formula, or you could be an elementary student who needs to figure it out by thinking about how many times the same number has to be added -- or the question might be directly related to learning about multiplication (which makes the answer almost obvious). At any rate, this definitely isn't "geometry and trig", so the category you used doesn't tell us anything.

On the other hand, giving only three terms of a sequence, without saying what kind of sequence it is, is not mathematics at all -- you are forced to guess, rather than deduce. (The next terms could be anything at all, because the term "sequence" means nothing more than "a list of numbers", with no pattern required.) That tells me that this question can't come from a higher level of math, where that fact would be known.

Whatever level it is, I've given you enough hints that you should be able to at least give it a try. The 1st term is 7, the 2nd term is 14, the 3rd term is 21, ... . What is the nth term in general?

 

[stapel]

The first three terms of a sequence are given:

. . .7, 14, and 21

Find the 42nd term.

Use the formula they gave you for arithmetic sequences. (here) Or, if for some reason the book or instructor hasn't covered this, figure out a rule that works for these first three terms, and then apply that rule thirty-nine more times (or use algebraic reasoning to greatly simplify your work).