How can we prove 2/c = 1/a+1/b without knowing anything about c,a and b?! So please post the complete question...

Wrong...question 2 - Xiu travels from town A to B at u km/h and then returns at v km/h. Town A is d km from town B

a) if it takes T hours to travel from A to B, find the time taken:

i) the entire trip in terms of T, u and v

attempt:

time = distance/ speed

u + v =speed back and forth

distance is d km

so d/u+v ??

(a) says "it takes T hours to travel from A to B".So there is no "back and forth" trip.

d km is the distance from A to B.

time = distance/ speed

Let the "back and forth trip" take time 't', then the total time is:

But , so:

Thus is the time taken for the entire trip in terms of T, u and v.

average speed = total distance/total timequestion 3- A man walks 70 km. He walks x km at 8 km/h and y km at 10km/h

a) fins his average speed in terms of x and y.

attempt:

average speed is = distance/ time

70/8x+10y ??