Answer:
Option C
Explanation:
We have,
225a2+9b2+25c2-75ac-45ab-15bc=0
⇒(15a)2+(3b)2+(5c)2−(15a)(5c)−(15a)(3b)−(3b)(5c)=0
⇒12[(15a−3b)2+(3b−5c)2+(5c−15a)2]=0
⇒15a=3b,3b=5c and 5c=15a
∴ 15a=3b=5c
⇒a1=b5=c3=λ(say)
⇒a=λ,b=5λ,c=3λ
Hence, a,b and c are in A.P