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India STEMS
2022 India STEMS
STEMS 2021-22 Math Cat A-B
A2 B4 C1
A2 B4 C1
Part of
STEMS 2021-22 Math Cat A-B
Problems
(1)
Another strange representation of a prime
Source: STEMS 2022 Math Cat A P3/Cat B P4/Cat C P1
1/24/2022
If there are integers
a
,
b
,
c
a,b,c
a
,
b
,
c
such that
a
2
+
b
2
+
c
2
−
a
b
−
b
c
−
c
a
a^2+b^2+c^2-ab-bc-ca
a
2
+
b
2
+
c
2
−
ab
−
b
c
−
c
a
is divisible by a prime
p
p
p
such that
gcd
(
p
,
a
2
+
b
2
+
c
2
−
a
b
−
b
c
−
c
a
p
)
=
1
\text{gcd}(p,\frac{a^2+b^2+c^2-ab-bc-ca}{p})=1
gcd
(
p
,
p
a
2
+
b
2
+
c
2
−
ab
−
b
c
−
c
a
)
=
1
, then prove that there are integers
x
,
y
,
z
x,y,z
x
,
y
,
z
such that
p
=
x
2
+
y
2
+
z
2
−
x
y
−
y
z
−
z
x
p=x^2+y^2+z^2-xy-yz-zx
p
=
x
2
+
y
2
+
z
2
−
x
y
−
yz
−
z
x
.
number theory