Answer:
D
Step-by-step explanation:
Remember, an=a1(r)^(n-1) where a1=first term or where n=1 and r=commmon ratio
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a2/a1=r
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so if you have the graph, find the y value coresponding to x=1 and that is a1
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find the y value coresponding to x=2 and taht is a2, do a2/a1 to get r
so like I was saying
well, each term is 1/2 of the previous
20/40=1/2
so r=1/2
and a1=40
so

is da equation