What is the product of the polynomials below?(3x3 + 9x)(x2 - 2) A. 3x5 + 3x3 - 18x B. 3x5 + 3x3 + 18 C. 3x5 - 6x3 + 9x2 - 18x D. 3x5 + 15x2 - 18x

The correct answer is:  [A]:  " 3x⁵  + 3x³ − 18x " .
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Explanation:
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Given: 
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→  " (3x³ + 9x) (x² − 2) " ;   Find this product.
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Note:
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(a + b) (c + d) = ac + ad + bc + bd ;
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→ As such:

→ " (3x³ + 9x) (x² − 2) "  =
 
        (3x³ * x²)  + (3x³ * -2) + (9x * x²) + (9x * -2) = 
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→ ( 3x⁽³⁺²⁾ ) + ( - 6x³ ) + ( 9x⁽¹⁺²⁾ )  +  ( -18x) ; 

=  3x⁵ − 6x³ + 9x³ − 18x ; 

Combine the "like terms" ; 

− 6x³ + 9x³ =  + 3x³  ;

And rewrite:
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 →  "  3x⁵  + 3x³ − 18x " ; 

 →  which is:  "Answer choice:  [A]:  " 3x⁵  + 3x³ − 18x " . ___________________________________________________