SOLUTION: The average rate of a round trip having a one way distance of d is given by the complex rational expression 2d/(d/r^1) + (d/r^2)in which r^1 and r^2 are the average rates on the ou

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Question 351886: The average rate of a round trip having a one way distance of d is given by the complex rational expression 2d/(d/r^1) + (d/r^2)in which r^1 and r^2 are the average rates on the outgoing and return trips, resectively. Simplify the expression. Then find your average rate if you drive to campus averaging 40 miles er hour and return home on the same route averaging 30 miles per hour.

Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
The average rate of a round trip having a one way distance of d is given by
the complex rational expression 2d/(d/r^1) + (d/r^2)in which r^1 and r^2 are
the average rates on the outgoing and return trips, resectively.
Simplify the expression.
:
I don't think 1 and 2 are exponents, you mean just r1 and r2, it seems to make
something fairly simple complicated.
:
%282d%29%2F%28%28d%2Fr1%29%2B%28d%2Fr2%29%29
I clicked the wrong thing, continuing:
Let ra = average rate for the round trip. write a time equation Time = dist/speed
:
Go time + return time = total time
d%2Fr1 + d%2Fr2 = %282d%29%2Fra
:
Then find your average rate if you drive to campus averaging 40 miles er hour
and return home on the same route averaging 30 miles per hour.
d%2F40 + d%2F30 = %282d%29%2Fra
divide thru by d and you have
1%2F40 + 1%2F30 = 2%2Fra
multiply by 120ra to clear the denominator
3ra + 4ra = 2(120)
7ra = 240
ra = 240%2F7
ra = 34.3 mph av for the round trip
:
Prove this using 100 mi as the distance, find the times:
100%2F40 + 100%2F30 = 200%2F34.3
2.5 + 3.333 = 5.833