The correct answer is: [A]: " 3x⁵ + 3x³ − 18x " .
_________________________________________
Explanation:
_________________________________________
Given:
_________________________________________
→ " (3x³ + 9x) (x² − 2) " ; Find this product.
_________________________________________
Note:
_________________________________________
(a + b) (c + d) = ac + ad + bc + bd ;
_________________________________________
→ As such:
→ " (3x³ + 9x) (x² − 2) " =
(3x³ * x²) + (3x³ * -2) + (9x * x²) + (9x * -2) =
_________________________________________
→ ( 3x⁽³⁺²⁾ ) + ( - 6x³ ) + ( 9x⁽¹⁺²⁾ ) + ( -18x) ;
= 3x⁵ − 6x³ + 9x³ − 18x ;
Combine the "like terms" ;
− 6x³ + 9x³ = + 3x³ ;
And rewrite:
___________________________________________________
→ " 3x⁵ + 3x³ − 18x " ;
→ which is: "Answer choice: [A]: " 3x⁵ + 3x³ − 18x " . ___________________________________________________
