If ab+bc+ca=0, then the value of 1a2−bc+1b2−ca+1c2−ab will be:
A.−1
B.a+b+c
C.abc
D.0
Correct option is D.0
Given: ab+bc+ca=0
Therefore,
⇒ab=−(bc+ca)...(i)
⇒bc=−(ab+ca)...(ii) and
⇒ca=−(ab+bc)...9(ii)
Now,
From (i),(ii) and (iii)
1a2−bc+1b2−ca+1c2−ab=1a2+(ab+ca)+1b2+(ab+bc)+1c2+(bc+ca)
=1a(a+b+c)+1b(a+b+c)+1c(a+b+c)
=bc+ac+ababc(a+b+c)
=0abc(a+b+c)
=0
Therefore, 1a2−bc+1b2−ca+1c2−ab=0