Question

the sum of (x+3) observations is (x^4 - 81) . find the mean of the observations.

Answer 1

Hi friend
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Your answer
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Sum of (x + 3) observations = (x⁴ - 81)

Mean will be =
$\frac{x {}^{4} - 81 }{x + 3} \\ \\ = \frac{(x {}^{2} ) {}^{2} - (9) {}^{2} }{(x + 3)} \\ \\ = \frac{(x { }^{2} - 9)(x {}^{2} + 9 )}{(x + 3)} \\ \\ = \frac{(x + 3)(x - 3)(x {}^{2} + 9)}{(x + 3)} \\ \\ = (x - 3)(x {}^{2} + 9)$

Therefore,
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The mean is (x - 3)(x² + 9)

HOPE IT HELPS

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Answer 2

hii

Sum of (x + 3) observation= (x⁴ - 81)

Mean = x⁴ - 81 / x -3
          = (x²)² - (9)² / x -3
          = (x²-9)( x²+9) / x -3
          = (x+3) (x-3) (x²+9) / x -3
          = (x-3) ( x²+9)
∴ (x-3) ( x²+9) is the mean ! 

hope this helps u!