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# Without actually calculating the cubes, find the value of the following: (ii) (28) ^ 3 + (- 15) ^ 3 + ( - 13) ^r 3

14.(ii) Without actually calculating the cubes, find the value of the following:
(ii)   $(28)^3 + (-15)^3 + (-13)^3$

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Given is   $(28)^3 + (-15)^3 + (-13)^3$

We know that

If   $x+y+z = 0$   then ,   $x^3+y^3+z^3 = 3xyz$

Here, $x = 28 , y = -15 \ \ an d \ \ z = -13$

$\Rightarrow x+y+z =28-15-13 = 0$

Therefore,

$(28)^3 + (-15)^3 + (-13)^3 = 3 \times (28)\times (-15) \times (-13) = 16380$

Therefore, value of  $(28)^3 + (-15)^3 + (-13)^3$  is  $16380$

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