Tuesday, July 23, 2013

Algebric identity



If a, b and c are all ≠ 0, and a + b + c = 0, then show that 
a2/bc +b2/ca + c2/ba = 3





Answer:
if a+ b + c = 0, then
we have (a + b) = -c
taking cube on each side of equation, we get
a3 + b3 + 3a2b + 3ab2 = -c3
or, a3 + b3 + c3 = -3ab(a + b)
or, a3 + b3 + c3 = -3ab(-c)
or, a3 + b3 + c3 = 3abc
 Dividing throughout by “abc”, we get
a2/bc +b2/ca + c2/ba = 3








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