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PEN A Problems
7
A 7
A 7
Source:
May 25, 2007
quadratics
LaTeX
modular arithmetic
Divisibility Theory
Problem Statement
Let
n
n
n
be a positive integer such that
2
+
2
28
n
2
+
1
2+2\sqrt{28n^2 +1}
2
+
2
28
n
2
+
1
is an integer. Show that
2
+
2
28
n
2
+
1
2+2\sqrt{28n^2 +1}
2
+
2
28
n
2
+
1
is the square of an integer.
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