SOLUTION: Alice is in a 20-km running race. She always runs the first half at an average speed of 2 km/h faster than the second half. Let x represent her speed in the first half. Determine a

Algebra ->  Rational-functions -> SOLUTION: Alice is in a 20-km running race. She always runs the first half at an average speed of 2 km/h faster than the second half. Let x represent her speed in the first half. Determine a      Log On


   

Question 1136891: Alice is in a 20-km running race. She always runs the first half at an average speed of 2 km/h faster than the second half. Let x represent her speed in the first half. Determine a simplified expression in terms of x for the total time needed for a race. I wrote this 20/x(x-2) but I can't do anything with it and it's incorrect.
Answer by ikleyn(52879) About Me  (Show Source):
You can put this solution on YOUR website!
.

One half of the race is 20/2 = 10 kilometers, same as the second half.


The time spent on the first half is  10%2Fx  hours.


The time spent on the second half is  10%2F%28x-2%29  hours  (since the speed there is (x-2) km/h).


Hence, the total time expression is


    Total time = 10%2Fx + 10%2F%28x-2%29    hours.

Having this basic expression, you can transform it in any (equivalent) way, on your choice.

Solved.