4/26/10

Test 1 Section 7 - #14 (page 417)

Set up a hangman-like set of blanks so that you can fill them in as you go:

__, __, __, __, __, __, __, __

Now, start to fill in what you know (the third and the sixth numbers):

__, __, 17, __, __, 77, __, __

When the question says the difference between two consecutive terms is always the same number, that means that we're counting up by that number (say we were counting by 2's, we'd have 2, 4, 6, 8, etc.).  What are we counting up by here?  How do we get from 17 to 77 in 3 steps?  We count up by 20's:

__, __, 17, 37, 57, 77, __, __

So all we need to do now is find what they asked for: the 8th term.  

__, __, 17, 37, 57, 77, 97, __
__, __, 17, 37, 57, 77, 97, 117
The eighth term is 117.

2 comments:

  1. How do you figure out what to count up by?

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  2. 77–17=60. Going up 60 in 3 steps means going up 20 per step (60/3=20)

    ReplyDelete