aschunyhung

14.08.2020 • 

Mathematics

A train is travelling at 30 mph towards a terminus which is 120 miles away. At the same time, a pigeon starts flying from the terminus towards the train. When it meets the train, it turns and flies back towards the terminus and, when it arrives there, it turns and flies back towards the train again. The pigeon flies at an average speed of 40 mph.

The pigeon continues to do this until the train reaches the terminus.

Assuming that no time was lost in the turnaround, how far (to the nearest 10 miles) does the pigeon fly altogether?

Ответ:

birdwithpurpleboots

08.08.2020

Mathematics

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For 2x^2 + 3x = -1 => 2x^2 + 3x + 1 = 0 => a = 2, b = 3, c = 1
b^2 - 4ac = 3^2 - (4 x 2 x 1) = 9 - 8 = 1

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