In order to solve this problem, you have to substitute x and y for each coordinate pair. which ever pair doesn't work with the equation is the answer.
y=3(1/2)^x
12=3(1/2)^-2 Β Β 12=3(4) Β 12=12 (correct)
3/8=3(1/2)^3 Β Β 3/8=3(1/8) Β 3/8=3/8 (correct)
3=3(1/2)^0 Β Β Β Β 3=3(1) Β Β Β 3=3 (correct)
9=3(1/2)^-1 Β Β Β 9=3(2) Β Β 9=6 (incorrect)
because 9β 6 we can see that (-1, 9) is the point that does not lie on the graphed equation