Difference between revisions of "1983 AIME Problems/Problem 2"

Line 13: Line 13:
 
----
 
----
  
* [[1983 AIME Problems/Problem |Previous Problem]]
+
* [[1983 AIME Problems/Problem 1|Previous Problem]]
* [[1983 AIME Problems/Problem |Next Problem]]
+
* [[1983 AIME Problems/Problem 3|Next Problem]]
 
* [[1983 AIME Problems|Back to Exam]]
 
* [[1983 AIME Problems|Back to Exam]]
  
 
[[Category:Intermediate Algebra Problems]]
 
[[Category:Intermediate Algebra Problems]]

Revision as of 23:45, 23 July 2006

Problem

Let $f(x)=|x-p|+|x-15|+|x-p-15|$, where $p \leq x \leq 15$. Determine the minimum value taken by $f(x)$ by $x$ in the interval $0 < p<15$.

Solution

It is best to get rid of the absolute value first.

Under the given circumstances, we notice that $|x-p|=x-p$, $|x-15|=15-x$, and $|x-p-15|=15+p-x$.

Adding these together, we find that the sum is equal to $30-x$, of which the minimum value is attained when $x=15$.

The answer is thus $015$.