Answer:
To solve this problem, we can use a system of equations.
We know the quadratic expression has the form
[tex]f(t)=at^{2}+bt[/tex]
Using points (1,12) and (4,0), we can form the following system to find a and b.
[tex]12=a+b[/tex]
[tex]0=16a+4b[/tex]
We need to divide the second equation by -4 and sum both equations
[tex]12=a+b\\0=-4a-b[/tex]
[tex]12=-3a\\a=\frac{12}{-3}\\ a=-4[/tex]
Then, we use this value to find the other variable
[tex]12=a+b\\12=-4+b\\b=12+4\\b=16[/tex]
[tex]f(t)=-4t^{2} +16t[/tex] or [tex]f(t)=-4t(t-4)[/tex]
According to this expression, after 2 seconds, the height is 16 feet.
[tex]f(2)=-4(2)(2-4)=-8(-2)=16[/tex]