Difference between revisions of "2006 AMC 12B Problems/Problem 8"

(Problem)
(Solution)
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<math>4x-4a=\frac{1}{4}x+b</math>
 
<math>4x-4a=\frac{1}{4}x+b</math>
  
<math>4*1-4a=\frac{1}{4}*1+b=2</math>
+
<math>4\cdot1-4a=\frac{1}{4}\cdot1+b=2</math>
  
 
<math>a=\frac{1}{2}</math>
 
<math>a=\frac{1}{2}</math>
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<math>a+b=\frac{9}{4} \Rightarrow \text{(E)}</math>
 
<math>a+b=\frac{9}{4} \Rightarrow \text{(E)}</math>
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== See also ==
 
== See also ==
 
{{AMC12 box|year=2006|ab=B|num-b=7|num-a=9}}
 
{{AMC12 box|year=2006|ab=B|num-b=7|num-a=9}}
 
{{MAA Notice}}
 
{{MAA Notice}}

Revision as of 20:49, 15 September 2016

Problem

The lines $x = \frac 14y + a$ and $y = \frac 14x + b$ intersect at the point $(1,2)$. What is $a + b$?

$\text {(A) } 0 \qquad \text {(B) } \frac 34 \qquad \text {(C) } 1 \qquad \text {(D) } 2 \qquad \text {(E) } \frac 94$

Solution

$4x-4a=y$

$4x-4a=\frac{1}{4}x+b$

$4\cdot1-4a=\frac{1}{4}\cdot1+b=2$

$a=\frac{1}{2}$

$b=\frac{7}{4}$

$a+b=\frac{9}{4} \Rightarrow \text{(E)}$

See also

2006 AMC 12B (ProblemsAnswer KeyResources)
Preceded by
Problem 7
Followed by
Problem 9
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

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