Toán Lớp 6: Tìm n €N ,n>1
a, n+3 chia hết cho n+1
b, n+4 chia hết cho n-1
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Toán Lớp 6: Tìm n €N ,n>1
a, n+3 chia hết cho n+1
b, n+4 chia hết cho n-1
Comments ( 2 )
=> n+1+2 vdots n+1
=>(n+1)+2 vdots n+1
=> 2 vdots n+1
=> n +1 in Ư(2)={-1,-2,1,2}
Mà n in N; n>1
=>n={∅}
b)n+4 vdots n-1
=> n-1+5 vdots n-1
=> (n-1)+5 vdots n-1
=> 5 vdots n-1
=> n-1 in Ư(5)={-1,-5,1,5}
Mà n in N; n>1
=>n={6}