Question

2n+1⋮n-3

n+5⋮2n-1

1001⋮n+1va n-1 ⋮15

Answer 1

Câu thứ nhất: 2n+1 chia hết cho n-3

2n-6+7 chia hết cho n-3

2( n-3) +7 chia hết cho n-3

Vì 2(n-3) chia hết cho n-3 nên 7 chia hết cho n-3.

Vậy n-3 \(\inƯ\left(7\right)=\left\{1;7\right\}\)

\(\Rightarrow n\in\left\{4;10\right\}\)

Answer 2

b: =>2n+10 chia hết cho 2n-1

=>2n-1+11 chia hết cho 2n-1

=>\(2n-1\in\left\{1;-1;11;-11\right\}\)

hay \(n\in\left\{1;0;6;-5\right\}\)

c: \(\Leftrightarrow\left\{{}\begin{matrix}n+1\in\left\{1;7;11;13;77;91;143;1001\right\}\\n\in\left\{16;31;...\right\}\end{matrix}\right.\)

=>\(n\in\left\{76\right\}\)