[填空题]
The downward speed, V 4:) sxvjt,yuwe;h0mwf d l.f2au o+w1, in metres per second, gained by a skydih-k7 wssjm 60xver during a jump is modelledj- w60xssk7h m by the function
V(t)=56−56$\times3$$^{-\frac{t}{4}}$,t≥0,where t, in seconds, is the time for which the skydiver is free falling in the air.
1.Write down the downward speed of the skydiver at t=0.
The line L is the horizontal asymptote to the graph. V =
2.Determine the equation of L.
The skydiver starts to feel no acceleration when he reaches the speed of 55 metres per second. y =
3.Find the time it takes for the skydiver to reach this speed. Give your answer correct to the nearest second. t ≈
