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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 6: 5n+1 chia hết cho n-1 3n+5 chia hết cho 2n+1

Toán Lớp 6: 5n+1 chia hết cho n-1
3n+5 chia hết cho 2n+1

Comments ( 1 )

  1. (5n+1) chia hết cho n-1
    5(n – 1) chia hết cho n-1
    =>(5n+1) – (5n-5) chia hết cho n-1
    =6 chia hết cho n-1 => n – 1 ∈ Ư(6) = {1,2,3,6}
    n – 1 =1 => n=2
    n – 1 =2 => n=3
    n – 1 =3 => n=4
    n – 1 =6 => n=7
         kl n ={2,3,4,7}
    b.2(3n+5) chia hết cho 2n+1
       3(2n+1) chia hết cho 2n+1
    =>(6n +10) – (6n+3) chia hết cho 2n+1
    =7 chia hết cho 2n+1
    =>2n +1 ∈ Ư(7)={1,7}
    2n + 1 = 1 =>n=0
    2n + 1 = 7 =>n=3
    kl n=0,3
     

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222-9+11+12:2*14+14 = ? ( )