genius ???, page-36

The question is worded mathematically incorrect.

Although its easy, these questions are usually worded as such:

6 'operation' 2= 63. or:
6*2=3.

the use of '+' is misleading.

notice that 6+5 is not equal to 5+6.

A general 'star' is usually used to denote an 'unknown' operation.

These questions are interesting though.

oddly, its not a 2d function, ie y=f(x).

its a 3d function, z=f(x,y)

For anyone interested, this has equation: f(x,y)=x(x+y)

Its graph is as follows (f(x,y) is vertical)