二次方程 函数The following function gives the height,h metres,of a
二次方程 函数 The following function gives the height,h metres,of a batted baseball as a function of the time,t seconds,since the ball was hit: h= -6(t-2.5)^2+ 38.5 a) How many seconds after it was hit did the ball hit the ground ,to the nearest second? 请列出主要的演算步骤和式子.