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Abstract Algebra: Theory and Applications · Problem 13
Polynomials — Thomas Judson
Mathematics — Abstract Algebra · chinese-remainder-theorem-rings
Problem Use the Chinese Remainder Theorem to solve each of the following systems of congruences.
(a)
x ≡ 2 ( m o d 5 ) x ≡ 6 ( m o d 11 ) \begin{aligned}
x &\equiv 2 \pmod{5}\\
x &\equiv 6 \pmod{11}
\end{aligned} x x ≡ 2 ( mod 5 ) ≡ 6 ( mod 11 )
(b)
x ≡ 3 ( m o d 7 ) x ≡ 0 ( m o d 8 ) x ≡ 5 ( m o d 15 ) \begin{aligned}
x &\equiv 3 \pmod{7}\\
x &\equiv 0 \pmod{8}\\
x &\equiv 5 \pmod{15}
\end{aligned} x x x ≡ 3 ( mod 7 ) ≡ 0 ( mod 8 ) ≡ 5 ( mod 15 )
(c)
x ≡ 2 ( m o d 4 ) x ≡ 4 ( m o d 7 ) x ≡ 7 ( m o d 9 ) x ≡ 5 ( m o d 11 ) \begin{aligned}
x &\equiv 2 \pmod{4}\\
x &\equiv 4 \pmod{7}\\
x &\equiv 7 \pmod{9}\\
x &\equiv 5 \pmod{11}
\end{aligned} x x x x ≡ 2 ( mod 4 ) ≡ 4 ( mod 7 ) ≡ 7 ( mod 9 ) ≡ 5 ( mod 11 )
(d)
x ≡ 3 ( m o d 5 ) x ≡ 0 ( m o d 8 ) x ≡ 1 ( m o d 11 ) x ≡ 5 ( m o d 13 ) \begin{aligned}
x &\equiv 3 \pmod{5}\\
x &\equiv 0 \pmod{8}\\
x &\equiv 1 \pmod{11}\\
x &\equiv 5 \pmod{13}
\end{aligned} x x x x ≡ 3 ( mod 5 ) ≡ 0 ( mod 8 ) ≡ 1 ( mod 11 ) ≡ 5 ( mod 13 )
Hint. (a) x ≡ 17 ( m o d 55 ) x \equiv 17 \pmod{55} x ≡ 17 ( mod 55 ) ; (c) x ≡ 214 ( m o d 2772 ) x \equiv 214 \pmod{2772} x ≡ 214 ( mod 2772 ) .
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