數學 微積分

If a ball is thrown straight up into the air with an initial velocity of 95 ft/s

it height in feet after t second is given by y = 95t - 16t^2 . Find the average velocity for the time period begining when t = 2 and lasting a: 0.1 seconds ? b: 0.01 seconds ? c: 0.001 seconds ? d: Finally based on the above results

guess what the instantaneous velocity of the ball is when t = 2 ? 知識把有些尾部的英文字母沒接起來 請自動接起來 謝謝感謝 幫忙的人
y(t)= 95t- 16t^2

y(2)= 126Qa: ∆t= 0.1 (delta t= 0.1) y(2.1)= 128.94 average velocity = (128.94 - 126)/0.1 =29.4Qb: ∆t = 0.01 (delta t= 0.01) y(2.01)=126.3084average velocity = (126.3084- 126)/0.01= 30.84Qc: ∆t= 0.001 (delta=0.001) y(2.001)=126.030984 average velocity= (126.030984- 126)/0.001= 30.984Qd: the instantaneous velocity is y