Write an exponential function y=ab^x whose graph passes through the points (1,3) and (2,12)

y = ?

y=3/4(4)^x

Step-by-step explanation:

hello :

the graph passes through the point (1,3) : when x=1  and  y=3  : 3= ab^1

the graph passes through the point (2,12) : when x=2  and  y=12  : 12= ab^2

so the system :  ab=3 ...(*)

                         ab² =12..(**)

ab² = b(ab) = 12   but : ab=3    so : (**) equivalent to     b(3)=12   b=12/3=4

now : ab= 3 and b=4    so : 4a=3  ... a=3/4

y=3/4(4)^x