If a,b,ca, b, ca,b,c are in GP, which of the following is true?
b2=acb^2 = acb2=ac
2b=a+c2b = a+c2b=a+c
1a,1b,1c\frac{1}{a}, \frac{1}{b}, \frac{1}{c}a1,b1,c1 are in GP
a+b=ca+b=ca+b=c