9514 1404 393
Answer:
(c) 27x^11 +51x^7 +9x^6 -60x^5 +17x^2 -20
Explanation:
As with many multiple-choice questions, you only need to look at something that will discriminate the correct answer from the wrong one.
The highest-degree product term is the product of the highest-degree terms in the factors:
(3x^5)(9x^6) = 27x^11
This matches choice C only.
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In case you're interested in actually performing the rest of the multiplication, the distributive property applies.
(1 +3x^5)(17x^2 +9x^6 -20)
= 1(17x^2 +9x^6 -20) +3x^5(17x^2 +9x^6 -20)
= 17x^2 +9x^6 -20 +51x^7 +27x^11 -60x^5
Writing these terms in order of decreasing exponents gives ...
= 27x^11 +51x^7 +9x^6 -60x^5 +17x^2 -20