Question 1136793
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<pre>
Let "a" be the first term of the progression and  "d" be the common difference.


Then from the condition you have these 2 equations


{{{a[9]}}} = a + 8d = -8

{{{a[17]}}} = a + 16d = 32.
</pre>


At this point I will stop my writing,  since from your post it is not clear to me if 32 is positive or negative; 
and I don't want to spend my time for nothing.


Learn how to write your posts in unambiguous way.


In this case you could easily write "-8" instead of saying "negative 8".


Do you know where the minus sign " - " is located in your keyboard ?



Keep in mind that you lost a rare and happy opportunity to learn from me, since you presented your post in inaccurate way.



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Regarding the post by @rothauserc, &nbsp;keep in mind that &nbsp;EVERYTHERE &nbsp;where he writes &nbsp;" a(0) ", &nbsp;it should be read as " a(1) ".