1.

If `a ,b ,c in R^+`, then the minimum value of `a(b^2+c^2)+b(c^2+a^2)+c(a^2+b^2)`is equal to`a b c``2a b c``3a b c``6a b c`A. abcB. 2abcC. 3abcD. 6abc

Answer» Correct Answer - D
`a (b^(2) + c^(2)) + b (c^(2) + a^(2)) + c (a^(2) + b^(2))`
`= ab^(2) + ac^(2) + bc^(2) + ba^(2) + ca^(2) + cb^(2)`
Using A.M `ge` G.M we get
`(ab^(2) + ac^(2) + bc^(2) + ba^(2) + ca^(2) + cb^(2))/(6) ge (a^(6) b^(6) c^(6))^(1//6)`
Or `a (b^(2) + c^(2)) + b(c^(2) + a^(2)) + c (a^(2) + b^(2)) ge 6 abc`


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