Question

If Y is directly proportional to X² and y=21 when x=2, find the value of y when X=4.

Answer 1

Explanation:

it means y/x^2=k

when y=21, x=2; k is 21/4.

when x=4, k is y/16.

k=21/4=y/16.

the next step is easy to see, you can do it.

Answer 2

The value of y will probably be 4.