Question

13. If ab + bc + ac = 0, then the value of
1
1
1
+
+
where a, b, c,
a? - bc62-ac c2 - ab
(a + b + c) = 0, is equal to
(1) -1
(2) a+b + c
(3) abc
(4) oo


pls answet

Answer 1

Answer:

the correct answer is a (I think but not sure)