Difference between revisions of "2008 AMC 12B Problems/Problem 7"

(Added Solution)
 
 
(6 intermediate revisions by 4 users not shown)
Line 1: Line 1:
==Problem 7==
+
==Problem==
For real numbers <math>a</math> and <math>b</math>, define <math>a\</math><math>b = (a - b)^2</math>. What is <math>(x - y)^2\</math><math>(y - x)^2</math>?
+
For real numbers <math>a</math> and <math>b</math>, define <math>a\textdollar b = (a - b)^2</math>. What is <math>(x - y)^2\textdollar(y - x)^2</math>?
  
 
<math>\textbf{(A)}\ 0 \qquad \textbf{(B)}\ x^2 + y^2 \qquad \textbf{(C)}\ 2x^2 \qquad \textbf{(D)}\ 2y^2 \qquad \textbf{(E)}\ 4xy</math>
 
<math>\textbf{(A)}\ 0 \qquad \textbf{(B)}\ x^2 + y^2 \qquad \textbf{(C)}\ 2x^2 \qquad \textbf{(D)}\ 2y^2 \qquad \textbf{(E)}\ 4xy</math>
  
==Solution==
+
==Solution 1 ==
  
 
<math>\left[ (x-y)^2 - (y-x)^2 \right]^2</math>
 
<math>\left[ (x-y)^2 - (y-x)^2 \right]^2</math>
Line 16: Line 16:
 
==See Also==
 
==See Also==
 
{{AMC12 box|year=2008|ab=B|num-b=6|num-a=8}}
 
{{AMC12 box|year=2008|ab=B|num-b=6|num-a=8}}
 +
{{MAA Notice}}

Latest revision as of 13:48, 15 February 2021

Problem

For real numbers $a$ and $b$, define $a\textdollar b = (a - b)^2$. What is $(x - y)^2\textdollar(y - x)^2$?

$\textbf{(A)}\ 0 \qquad \textbf{(B)}\ x^2 + y^2 \qquad \textbf{(C)}\ 2x^2 \qquad \textbf{(D)}\ 2y^2 \qquad \textbf{(E)}\ 4xy$

Solution 1

$\left[ (x-y)^2 - (y-x)^2 \right]^2$

$\left[ (x-y)^2 - (x-y)^2 \right]^2$

$[0]^2$

$0 \Rightarrow \textbf{(A)}$

See Also

2008 AMC 12B (ProblemsAnswer KeyResources)
Preceded by
Problem 6
Followed by
Problem 8
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 AMC 12 Problems and Solutions

The problems on this page are copyrighted by the Mathematical Association of America's American Mathematics Competitions. AMC logo.png