What Is The Value of The Equation ?

If m + n = -2 then the value of m3 + n3 -6 mn is

  1. 8
  2. 4
  3. -8
  4. -4
Anurag Mishra Professor Asked on 21st July 2015 in Maths.
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1 Answer(s)

Answer: (3) – 8
Explanation:-
m + n = – 2
Cubes of both side,
(m + n)3 = (- 2)3
Formula-
(a + b)3 = a3 + b3 + 3ab(a + b)
m3 + n3 + 3 x mn(m+ n) = (-2) x (-2) x (-2)
m3 + n3 + 3 mn(- 2) = – 8
m3 + n3 – 6 mn = – 8
Hence, the answer is (3) -8

Anurag Mishra Professor Answered on 21st July 2015.
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