Steve goes on a 40-km bike ride. he covers the first half of the distance averaging a speed of 15 km/hr. in order to average 20 km/hr for the entire trip, how many kilometers per hour must his average speed be during the second half of the trip?

Speed required to cover second half of distance = 30 km/hr

Step-by-step explanation:

Total distance Steve traveled = 40 km

He covers the first half of the distance averaging a speed of 15 km/hr.

So he covers 20 km at a speed of 15 km/hr.

We need to find in order to average 20 km/hr for the entire trip , how many kilometers per hour must his average speed be during the second half of the trip.

So he need to cover second half distance in (2 - 1.33) hours = 0.67 hours.

Speed required to cover second half of distance = 30 km/hr

f(x) = x^3 -2x^2 -3x

x( x^2 -2x-3)

x( x^2 +x -3x -3)

x( x(x+1) -3(x+1))

x( x-3)( x+1)

so zeroes are 0, 3,-1

its (2) option