Difference between revisions of "2011 AMC 10A Problems/Problem 7"

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<math>\sqrt{x}-8=0</math> is true for <math>x = 64</math>
 
<math>\sqrt{x}-8=0</math> is true for <math>x = 64</math>
 +
 +
<math>|-3x|-4=0</math> is true for <math>x = \frac{4}{3}, -\frac{4}{3}</math>
  
 
Therefore, the answer is B.
 
Therefore, the answer is B.
  
<math>|-3x|-4=0</math> is true for <math>x = \frac{4}{3}, -\frac{4}{3}</math>
 
 
== See Also ==
 
== See Also ==
 
{{AMC10 box|year=2011|ab=A|num-b=6|num-a=8}}
 
{{AMC10 box|year=2011|ab=A|num-b=6|num-a=8}}

Revision as of 10:12, 5 July 2012

Problem 7

Which of the following equations does NOT have a solution?

$\text{(A)}\:(x+7)^2=0$

$\text{(B)}\:|-3x|+5=0$

$\text{(C)}\:\sqrt{-x}-2=0$

$\text{(D)}\:\sqrt{x}-8=0$

$\text{(E)}\:|-3x|-4=0$


Solution

$|-3x|+5=0$ has no solution because absolute values output positives and this equation implies that the absolute value could output a negative.

Further: $(x+7)^2 = 0$ is true for $x = -7$

$\sqrt{-x}-2=0$ is true for $x = -4$

$\sqrt{x}-8=0$ is true for $x = 64$

$|-3x|-4=0$ is true for $x = \frac{4}{3}, -\frac{4}{3}$

Therefore, the answer is B.

See Also

2011 AMC 10A (ProblemsAnswer KeyResources)
Preceded by
Problem 6
Followed by
Problem 8
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All AMC 10 Problems and Solutions
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