If the graph of y=b^x goes thru the point (-2,9), determine b.

a. -9/2
b. -3
c. 1/3
d. 3

Just plug in the values for the point
9 = b^(-2) = 1/ (b^2)

Since 9 = 1 / ( 1/9), it must be that b^2 = 1/9. So b = + or - 1/3.

9 = b^-2

9 = 1/b^2

b^2 = 1/9

b = 1/3, c