If `x^yxxy=1215` where `x,y in 1 and y ne 1`, then find xy.

If x = y^(1//a), y = z^(1//b) and z = x^(1//c) where x ne 1 y ne 1, z ne 1 , then what is the value of abc ?

If x^yxxy^x=72 , then find the sum of x and y where x and y are positive integers (x ne 1 and y ne 1) .

If (2)/(x) + (3)/(y) = (9)/( xy ) and (4)/(x) + (9)/(y) = (21)/(xy) where x ne 0 and y ne 0, that what is the value of x + y ?

Let be a real function satisfying f(x)+f(y)=f((x+y)/(1-xy)) for all x ,y in R and xy ne1 . Then f(x) is

Let be a real function satisfying f(x)+f(y)=f((x+y)/(1-xy)) for all x ,y in R and xy ne1 . Then f(x) is