Find the value of k for which the equation x2 + k(2x + k − 1) + 2 = 0 has real and equal roots.
If the equation (1 + m2) x2 + 2mcx + c2 – a2 = 0 has equal roots then show that c2 = a2 (1 + m2).
Speed of a boat in still water is 15 km/h. It goes 30 km upstream and returns back at the same point in 4 hours 30 minutes. Find the speed of the stream.
A plane left 30 minutes late than its scheduled time and in order to reach the destination 1500 km away in time, it had to increase its speed by 100 km/h from the usual speed. Find its usual speed.
Let the usual speed of the plane be x km/hr
Time taken to cover 1500 km with usual speed, t1 =
Time taken to cover 1500 km with speed of (x +100) km/hr, t2
Difference between t1 - t2 =30 min = 1/2
But speed can't be negative
Hence, usual speed 500 km/hr.
A motor boat whose speed is 18 km/hr in still water 1 hr more to go 24 km upstream than to return downstream to the same spot. Find the speed of the stream.
A train travels at a certain average speed for a distance of 63 km and then travels at a distance of 72 km at an average speed of 6 km/hr more than its original speed. It takes 3 hours to complete the total journey, what is the original average speed ?