If the arithmetic mean of two numbers be A and geometric mean be G, then the numbers will be
A.M. = a+b2 = A and G.M. = √ab = G
On solving a and b are given by the values
A ±√(A+G)(A−G).
Trick : Let the numbers be 1, 9. Then A = 5 and G = 3. Now put these values in options.
Here (c) ∴5±√8×2 i.e. 9 and 1