Temperature vertex form question

Question

The temperature  y​  (in degrees Fahrenheit) after  t  months can be modeled by the function y=-4t^2+16t +20 , where 1≤t≤12​ .

a.  Write the function in vertex form.y=______

b.  Find the maximum temperature during the year.

The maximum temperature is _  degrees Fahrenheit.

Answer 1

a. y=f(-b/2a) where you find x=-b/2a

b=16 and a=4

=-16/8, x=-2

b. Substituting in given expression, x=t

4(-2)^2+16(-2)+20=16-32+20=4

maximum temperature is 4 degrees F