Q8 of 176 Page 20

If a, b, c are in G.P., prove that :

Now, as a,b,c are in GP.

∴ b² = ac …(1)

Put in the LHS of the given equation to be proved –

⇒ LHS =

⇒ LHS = {putting b² = ac }

⇒ LHS = a³ + b³ + c³ = RHS ...(Hence Proved)

The sum of three numbers in G.P. is 56. If we subtract 1, 7, 21 from these numbers in that order, we obtain an A.P. Find the numbers.

If a, b, c are in G.P., prove that :

a(b² + c²) = c(a² + b²)

If a, b, c are in G.P., prove that :