Difference between revisions of "1998 AJHSME Problems/Problem 2"

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== Problem 2 ==
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== Problem ==
  
 
If <math>\begin{tabular}{r|l}a&b \\ \hline c&d\end{tabular} = \text{a}\cdot \text{d} - \text{b}\cdot \text{c}</math>, what is the value of <math>\begin{tabular}{r|l}3&4 \\ \hline 1&2\end{tabular}</math>?
 
If <math>\begin{tabular}{r|l}a&b \\ \hline c&d\end{tabular} = \text{a}\cdot \text{d} - \text{b}\cdot \text{c}</math>, what is the value of <math>\begin{tabular}{r|l}3&4 \\ \hline 1&2\end{tabular}</math>?
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Plugging in values for <math>a</math>, <math>b</math>, <math>c</math>, and <math>d</math>, we get
 
Plugging in values for <math>a</math>, <math>b</math>, <math>c</math>, and <math>d</math>, we get
  
<math>a=3</math>
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<math>a=3</math>,
<math>b=4</math>
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<math>b=4</math>,
<math>c=1</math>
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<math>c=1</math>,
<math>d=2</math>
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<math>d=2</math>,
  
<math>a\timesd=3\times2=6</math>
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<math>a\times d=3\times2=6</math>
  
<math>b\timesc=4\times1=4</math>
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<math>b\times c=4\times1=4</math>
  
 
<math>6-4=2</math>
 
<math>6-4=2</math>
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* [[AJHSME Problems and Solutions]]
 
* [[AJHSME Problems and Solutions]]
 
* [[Mathematics competition resources]]
 
* [[Mathematics competition resources]]
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{{MAA Notice}}

Latest revision as of 15:40, 20 October 2016

Problem

If $\begin{tabular}{r|l}a&b \\ \hline c&d\end{tabular} = \text{a}\cdot \text{d} - \text{b}\cdot \text{c}$, what is the value of $\begin{tabular}{r|l}3&4 \\ \hline 1&2\end{tabular}$?

$\text{(A)}\ -2 \qquad \text{(B)}\ -1 \qquad \text{(C)}\ 0 \qquad \text{(D)}\ 1 \qquad \text{(E)}\ 2$

Solution

Plugging in values for $a$, $b$, $c$, and $d$, we get

$a=3$, $b=4$, $c=1$, $d=2$,

$a\times d=3\times2=6$

$b\times c=4\times1=4$

$6-4=2$

$\boxed{E}$

See also

1998 AJHSME (ProblemsAnswer KeyResources)
Preceded by
Problem 1
Followed by
Problem 3
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
All AJHSME/AMC 8 Problems and Solutions

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