Discussion

Explanation:

f(x/y) = f(x) − f(y) 
 
Putting x = y, we get,
 
f(1) = f(x) − f(x) = 0
 
Putting x = 1 and y = 1/x, we get,
 
f(x) = f(1) − f(1/x) = 0 − f(1/x)
 
∴ f(1/x) = −f(x) 
 
Also, putting x = x and y = 1/x, we get,
 
f(x²) = f(x) − f(1/x) = f(x) − (−f(x))
 
∴ f(x²) = 2f(x)
 
Now, f(2/72) = f(1/36) = - f(36) = -f(6²) = -2f(6)
 
Hence, option (c).

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