Question 473754: A boat travels 30 miles upstream and 30 miles downstream. The total time for both parts of the trip is 8 hours. the speed of the boat in still water is 8 mph. Find the speed of the current.
I have worked this problem 2 different ways and came up with 2 different answers both with radicals.
1. 30=(8+r)t <~~ I solved this one for t=30/(8+r)
30=(8-r)t
30=(8-r)(30/(8+r) the answer I got was 8+or- 2(squareroot of 15)
2. I used one from the website as a reference and worked it like this...
Current = X
upstream - x+8
downstream - 8-x
30/(x+8)+30/(8-x)= 8
LCM=(x+8)(8-x)
the answer I got was 2(squareroot of 31)
Where am I going wrong!?
Answer by ankor@dixie-net.com(22740)   (Show Source):
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