Question

The sequence of three number a,b,c are in ap whose sum is 18. If a and b are each increased by 4 and c is increased by 36 the new numbers form a gp find a,b,c

Answer 1

Let the last three numbers be a,a+6,a+12, so that the first three numbers are a+12,a,a+6. As these are in G.P.

a2=(a+12)(a+6)⇒a=−4

Common ratio is −2