a , b , c , d are in H . P .
b is the H . M of a ,and c are there A . M is a+b2 and G . M is √ac
c is the H . m of b and d are their A . M is b+d2 and G . M is √bd
Also the A > G > M where A , G , H are respectively means
∴a+c2>bandb+d2>c∵A>H
Add ,a+c2+b+d2>B+cora+b+c+d>2ab+2cOra+b>b+c. Thisis(b)√ac>band√bd>c∵G>H
Multipy ∴√Ac√bd>bcoracbd>b2c2orad>bc This is (a)