Difference between revisions of "1968 AHSME Problems/Problem 14"

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\text{(E) } x</math>
 
\text{(E) } x</math>
  
== Solution ==
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== Solution 1 ==
 
We see after multiplying the first equation by <math>y</math>, that  
 
We see after multiplying the first equation by <math>y</math>, that  
  
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~SirAppel
 
~SirAppel
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 +
== Solution 2 ==
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We can first combine the fraction on the second equation, which is
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<math>y=\dfrac{x+1}{x}.</math>
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Then, substituting the value of <math>x</math> from the first equation, we can get
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<math>y=\dfrac{1+\dfrac{1}{y}+1}{1+\dfrac{1}{y}}.</math>
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Then, multiplying the denominator on both sides, we get
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<math>y+1=2+\dfrac{1}{y} \implies y=1+\dfrac{1}{y}</math> which is equivalent to the value of <math>x</math> that was originally provided, giving the final answer of <math>\fbox{E}.</math>
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~TurtleGod7
  
 
== See also ==
 
== See also ==

Latest revision as of 03:01, 10 July 2025

Problem

If $x$ and $y$ are non-zero numbers such that $x=1+\frac{1}{y}$ and $y=1+\frac{1}{x}$, then $y$ equals

$\text{(A) } x-1\quad \text{(B) } 1-x\quad \text{(C) } 1+x\quad \text{(D) } -x\quad \text{(E) } x$

Solution 1

We see after multiplying the first equation by $y$, that

$xy=y+1.$

Similarly, we see that after multiplying the second equation by $x$, we get that

$xy=x+1.$

Thus $x+1=y+1 \implies x=y$, giving us our final answer of $\fbox{E}.$

~SirAppel

Solution 2

We can first combine the fraction on the second equation, which is

$y=\dfrac{x+1}{x}.$

Then, substituting the value of $x$ from the first equation, we can get

$y=\dfrac{1+\dfrac{1}{y}+1}{1+\dfrac{1}{y}}.$

Then, multiplying the denominator on both sides, we get

$y+1=2+\dfrac{1}{y} \implies y=1+\dfrac{1}{y}$ which is equivalent to the value of $x$ that was originally provided, giving the final answer of $\fbox{E}.$

~TurtleGod7

See also

1968 AHSC (ProblemsAnswer KeyResources)
Preceded by
Problem 13
Followed by
Problem 15
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35
All AHSME Problems and Solutions

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