Question

( x - 1) ϵ BC ( 4,5,6) và x < 400

( x - 1) ϵ BC ( 4,5,6) và ⋮ 7; x ≤ 400

Answer 1

1) \(\left(x-1\right)\in BC\left(4;5;6\right)\&x< 400\left(1\right)\)

\(BCNN\left(4;5;6\right)=60\)

\(\Rightarrow BC\left(4;5;6\right)=\left\{60;120;180;240;300;360;420...\right\}\)

\(\left(1\right)\Rightarrow x-1\in\left\{59;119;179;239;299;359\right\}\left(2\right)\)

b) \(\left(x-1\right)\in BC\left(4;5;6\right),⋮7\&x< 400\left(3\right)\)

\(\left(2\right);\left(3\right)\Rightarrow x-1\in\left\{119\right\}\)