If f(x)=7x2−15, then find the value of f(3) − f(5).
If f(x) satisfies f(x+y) = f(x) + f(y) and f(5) = 15 then find f(3)?
If f (x) is a cubic polynomial such that f (1)=1,f (2)=2,f (3)=3 and f (4)=16. Find the value of f (5).