If a, b,and c are in G.P. and x, y, respectively, be arithmetic means between a, b and b, c, then the value of ax+cyis
2
Given, b2=ac and x=a+b2,y=b+c2.Therefore,
ax+cy=2aa+b+2cb+c
=2a(b+c)+2c(a+b)(a+b)(b+c)
=22ac+ab+bcab+ac+b2+bc
=22ac+ab+bc2ac+ab+bc
=2