Difference between revisions of "1980 AHSME Problems/Problem 2"

(Solution)
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<math>\text{(A)} \ 5 \qquad \text{(B)} \ 7 \qquad \text{(C)} \ 12 \qquad \text{(D)} \ 17 \qquad \text{(E)} \ 72</math>
 
<math>\text{(A)} \ 5 \qquad \text{(B)} \ 7 \qquad \text{(C)} \ 12 \qquad \text{(D)} \ 17 \qquad \text{(E)} \ 72</math>
  
== Solution ==
+
== Solution 1==
  
 
It becomes <math> (x^{8}+...)(x^{9}+...) </math> with 8 being the degree of the first factor and 9 being the degree of the second factor, making the degree of the whole thing 17, or <math>\boxed{(D)}</math>
 
It becomes <math> (x^{8}+...)(x^{9}+...) </math> with 8 being the degree of the first factor and 9 being the degree of the second factor, making the degree of the whole thing 17, or <math>\boxed{(D)}</math>
  
 +
==Solution 2==
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 +
First note that note that <math>deg(P(x))^n = ndeg(P(x))</math> and that <math>deg(P(x)Q(x)) = deg(P(x))+deg(Q(x))</math>.
  
 
== See also ==
 
== See also ==
 
{{AHSME box|year=1980|num-b=1|num-a=3}}
 
{{AHSME box|year=1980|num-b=1|num-a=3}}
 
{{MAA Notice}}
 
{{MAA Notice}}

Revision as of 20:32, 11 December 2014

Problem

The degree of $(x^2+1)^4 (x^3+1)^3$ as a polynomial in $x$ is

$\text{(A)} \ 5 \qquad \text{(B)} \ 7 \qquad \text{(C)} \ 12 \qquad \text{(D)} \ 17 \qquad \text{(E)} \ 72$

Solution 1

It becomes $(x^{8}+...)(x^{9}+...)$ with 8 being the degree of the first factor and 9 being the degree of the second factor, making the degree of the whole thing 17, or $\boxed{(D)}$

Solution 2

First note that note that $deg(P(x))^n = ndeg(P(x))$ and that $deg(P(x)Q(x)) = deg(P(x))+deg(Q(x))$.

See also

1980 AHSME (ProblemsAnswer KeyResources)
Preceded by
Problem 1
Followed by
Problem 3
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