Question

Write an exponential function in the form y=ab^x that goes through points (0,10) and (2,490).

Answer 1

Time given to cover 40 km upstream = 3(time taken to cover dowmstream)

⇒40/ (5-x) km/hr = 3(5+x)

⇒1/(5-x)=3(5+x)

⇒5+x=15-3x

⇒x+3x=15-5

⇒4x=10

⇒X=10/4

⇒X=5/2

∴x=2.5 km/hr