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National and Regional Contests
Moldova Contests
JBMO TST - Moldova
2013 Junior Balkan Team Selection Tests - Moldova
2
{x \in N | x \in 4a + 7b, a, b \in N}, {x \in N | x\ne 3a + 11b, a, b \in N }
{x \in N | x \in 4a + 7b, a, b \in N}, {x \in N | x\ne 3a + 11b, a, b \in N }
Source: 2013 Moldova JBMO TST p2
February 25, 2021
Sets
number theory
Problem Statement
Determine the elements of the sets
A
=
{
x
∈
N
∣
x
≠
4
a
+
7
b
,
a
,
b
∈
N
}
A = \{x \in N | x \ne 4a + 7b, a, b \in N\}
A
=
{
x
∈
N
∣
x
=
4
a
+
7
b
,
a
,
b
∈
N
}
,
B
=
{
x
∈
N
∣
x
≠
3
a
+
11
b
,
a
,
b
∈
N
}
B = \{x \in N | x\ne 3a + 11b, a, b \in N\}
B
=
{
x
∈
N
∣
x
=
3
a
+
11
b
,
a
,
b
∈
N
}
.
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