The given equation is [tex]h(t)=-16t^2+80t+4[/tex] where h is the height, in feet, of a ball and t is the time, in seconds.
Part a: The height of the ball when t = 2 seconds:
The height of the ball above the ground 2 seconds after it is released can be determined by substituting t= 2 in the equation [tex]h(t)=-16t^2+80t+4[/tex], we get;
[tex]h(2)=-16(2)^2+80(2)+4[/tex]
Simplifying the terms, we get;
[tex]h(2)=-64+160+4[/tex]
[tex]h(2)=100[/tex]
Thus, the height of the ball after 2 seconds is 100 feet.
Part b: The height of the ball when t = 4 seconds:
The height of the ball above the ground 4 seconds after it is released can be determined by substituting t = 4 in the equation [tex]h(t)=-16t^2+80t+4[/tex], we get;
[tex]h(4)=-16(4)^2+80(4)+4[/tex]
Simplifying the terms, we get;
[tex]h(4)=-256+320+4[/tex]
[tex]h(4)=68[/tex]
Thus, the height of the ball after 4 seconds is 68 feet.