. If p + q + r = 0 then the value of
If p + q + r = 0 then the value of 
will be
A. 3pqr
B. 
C. 6
D. - 6
Best Answer
Answer ||| D
Solution |||
Given p + q + r = 0
⇒ q + r = - p
And p + r = - q
And p + q = - r.
= 
- - - - - - - - (1)
As p + q + r = 0
p + q = - r
cubing on both the sides,
(p + q)3 = - r3
So p3 + q3 + 3p2q + 3pq2 = - r3
p3 + q3 + r3 = - 3pq(p + q) - - - - - - - - -(2)
Substituting equation 2 in 1,
= 
As p + q = - r
So 
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