Difference between revisions of "1957 AHSME Problems/Problem 3"

(Created page with "hbkhbkhb")
 
m (typo fix)
 
(One intermediate revision by one other user not shown)
Line 1: Line 1:
hbkhbkhb
+
== Problem 3==
 +
 
 +
The simplest form of <math>1 - \frac{1}{1 + \frac{a}{1 - a}}</math> is:
 +
 
 +
<math>\textbf{(A)}\ {a}\text{ if }{a\not= 0} \qquad \textbf{(B)}\ 1\qquad
 +
\textbf{(C)}\ {a}\text{ if }{a\not=-1}\qquad
 +
\textbf{(D)}\ {1-a}\text{ with not restriction on }{a}\qquad
 +
\textbf{(E)}\ {a}\text{ if }{a\not= 1}  </math>
 +
 
 +
==Solution==
 +
We have <math>1 - \frac{1}{1 + \frac{a}{1 - a}} = 1 - \frac{1}{\frac{1}{1-a}} = 1 - \frac{1-a}{1} = a</math> for almost all <math>a</math>. However, the first step is invalid when <math>a=1</math>, and each step is valid otherwise, so the answer is (E).
 +
 
 +
==See Also==
 +
 
 +
{{AHSME 50p box|year=1957|num-b=2|num-a=4}}
 +
{{MAA Notice}}

Latest revision as of 08:04, 25 July 2024

Problem 3

The simplest form of $1 - \frac{1}{1 + \frac{a}{1 - a}}$ is:

$\textbf{(A)}\ {a}\text{ if }{a\not= 0} \qquad \textbf{(B)}\ 1\qquad  \textbf{(C)}\ {a}\text{ if }{a\not=-1}\qquad \textbf{(D)}\ {1-a}\text{ with not restriction on }{a}\qquad \textbf{(E)}\ {a}\text{ if }{a\not= 1}$

Solution

We have $1 - \frac{1}{1 + \frac{a}{1 - a}} = 1 - \frac{1}{\frac{1}{1-a}} = 1 - \frac{1-a}{1} = a$ for almost all $a$. However, the first step is invalid when $a=1$, and each step is valid otherwise, so the answer is (E).

See Also

1957 AHSC (ProblemsAnswer KeyResources)
Preceded by
Problem 2
Followed by
Problem 4
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 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
All AHSME Problems and Solutions

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