[填空题]
The downward speed, V, x(wm f3y-gl+ min metre 8expm+ikemniq 1,p4 7x2wmswz9,,mfs per second, gained by a skydiver during a jump is modellei i, 9xwxmmwz18nkm sq,e7 f4e2,p+p md 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 ≈