Find the exponential function f(x)=a(b)^x

Question

Whose points go thru (0,4) and (2,16)

Whose points go thru (-2,768) and (2,3)

Answer 1

(0,4)

y=ab^x

4=a

y=4b^x

16=4b^2

b=2

y=4(2^x)

(2,3)

y=ab^x

3=ab^2

768=a/b^2

b^2 =3/a= a/768

a^2=3(768)

a=sqr2304=48

b=sqr(3/48)=1/4

y=48(.25^x)