If x 2 and y ​2 are directly proportional, and x = 2 when y = 3, then what is y when x =3?

Directly proportional means    x^2 = k y^2       

                                                2^2 = k (3^2)

                                                   4 = k 9

                                                   k = 4/9

 

x^2 = 4/9 y^2

SO when x = 3

 

3^2 = 4/9 y^2

9 (9/4) = y^2

81/4 = y^2         Take the positive root

y = 9/2     when x = 3