Question 1192001

Arithmetic Series Question:
Determine the number of terms in the following arithmetic sequence.

2x + y, 3x + 4y, 4x + 7y,...10x + 25y

Textbook answer is 10.

Can someone please tell me how to get 10? Thank you.
<pre>10 is WRONG.

Let's JUST use each term's 1st expression to get m=number of terms.
1st term's first expression: 2x
2nd term's first expression: 3x
3rd term's first expression: 4x
It's quite clear that d (DIFFERENCE) in terms ix x

Again, using JUST the 1st expression of each term, and applying the number-of-terms formula:
{{{(Last - First + d)/d}}}, we get: {{{highlight_green(matrix(1,5, (10x - 2x + x)/x, "=", 9x/x, "=", highlight(matrix(1,2, 9, terms))))}}}

You could also LIST all terms, although this involves a little bit more work!

Don't know how an answer of 10 terms was derived!

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