Function notation confusion

[Bogogogo]

I solved out this problem by assuming that the function is f(r)=pi(r)^2
However my answers were all wrong
I am unsure as to where I messed up.

 

[Dr.Peterson]

They emphasize function notation, and you have not used that.

I think what they are asking for (an example would have helped) is, for example, in part (a), "f(4.8)". They don't want you to work out what the function actually is, but to demonstrate an understanding of the notation itself.

So, basically, everywhere you used pi r^2, just use f(r).

 

[willyengland]

Perhaps you should include units?