Raj and Dev leave the school at 3:30 PM and cycle in opposite direction. If their speeds are 5km/hr and 7km/hr respectively, at what time they will be 18 km apart?

They will be 18 km apart at 5 pm.

Step-by-step explanation:

Speed of Raj is 5km/hr and speed of Dev is 7km/hr

Since they are going in opposite direction,

So, every 1 hours there difference will be (7 + 5) km = 12 km

Now, they will be apart 18 km distance 18/12 hours = 1 hour 30 min

The time will be 3:30 PM + 1 hour 30 min = 5 :00 PM

x =±sqrt(1/3)

step-by-step explanation:

x+4/6x=1/x

multiply each side by 6x to get rid of the fractions

6x*(x+4/6x)=1/x*6x

distribute

6x^2 +4 = 6

subtract 4 from each side

6x^2 +4-4 = 6-4

6x^2 =2

divide by 6

6x^2/6 = 2/6

x^2 = 1/3

take the square root of each side

sqrt(x^2) = ±sqrt(1/3)

x =±sqrt(1/3)