The sketch shows part of the graph y=ab^x

Answer:
a = 3, b = 2
[tex]y = 3\cdot 2^x[/tex]
Step-by-step explanation:
[tex]y = ab^x\\3 = ab^0\\12 = ab^2\\~\\3=ab^0=a\cdot 1 = a\\a = 3\\~\\12 = ab^2 = 3b^2\\4 = b^2\\b = 2 \vee b = -2[/tex]
but we know from the graph being defined and positive, that b cannot be -2
b = 2