Question 1199475
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The 12th term is the 7th term, multiplied by the common ratio 12-7 = 5 times.  Use the given information to determine the common ratio.<br>
-1792 = 56(r^5)
r^5 = -1792/56 = -32
r = -2<br>
The 7th term is the first term, multiplied by the common ratio 7-1 = 6 times.  Use the given 7th term and the common ratio of -2 to find the first term.<br>
56 = a((-2)^6)
56 = 64a
a = 56/64 = 7/8<br>
ANSWERS:  common ratio -2; first term 7/8<br>