adam is about to embark on a journey on a narrow country lane that covers 32 km and decides to go at x km/h. on second thoughts, he calculates that if he increases the speed by 4km/h, his journey time can be cut down by 4 hrs. find x.
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Distance = 32 km
When the speed is x km/h
The time taken = 32/x h
The speed increased by 4 km/h then speed will become (x+4) km/h
Time taken = 32/x+4 h
32/x - 32/x+4 = 4
128/x(x+4) = 4
x² + 4x = 32
x² + 4x - 32 = 0
x² + 8x - 4x - 32 = 0
x(x+8) -4(x+8) = 0
(x-4)(x+8) = 0
x = 4 or -8
Speed of the journey would be 4km/h
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