Question

[Nguyen Vu trong hieu]

Tim so tu nhien x biet :

a) 10 chia het cho n

b) 12 chia het cho n - 1

c) 20 chia het cho 2.n + 1

d) n + 5 chia het cho n + 1 

e) n+7 chia het cho n + 2

f) 2.n + 5 chia het cho 2.n + 1 

tra loi nhanh dum minh nhe

Answer 1

[❤ Hoa ❤]

\(a,10⋮n\Rightarrow n\inƯ\left(10\right)=\left\{\pm1;\pm2;\pm5\pm10\right\}.\)

\(\Rightarrow n\in\left\{\pm1;\pm2;\pm5;\pm10\right\}\)

\(b,12⋮n-1\Rightarrow n-1\inƯ\left(12\right)\left\{\pm1;\pm2;\pm3\pm4;\pm6;\pm12\right\}\)

Answer 2

[❤ Hoa ❤]

\(d,n+5⋮n+1\Rightarrow n+1+4⋮n+1.\)

mà \(n+1⋮n+1\Rightarrow4⋮n+1\)

\(\Rightarrow n+1\inƯ\left(4\right)=\left\{\pm1;\pm2;\pm4\right\}\)

n+1 = 1 => n = 0

n + 1 = -1 => -2 

..... tương tự vs 2; -2 ; 4 ; -4 

\(e,n+7⋮n+2\Rightarrow n+2+5⋮n+2\)

mà \(n+2⋮n+2\Rightarrow5⋮n+2\)

\(\Rightarrow n+2\inƯ\left(5\right)=\left\{\pm1;\pm5\right\}\)

n+2 = 1 => n = -1

n + 2 = -1 => n = 3 

.... tương tự vs 5 và -5 

\(f,2n+5⋮2n+1\Rightarrow2n+1+4⋮2n+1\)

\(\Rightarrow2n+1⋮2n+1\Rightarrow4⋮2n+1\)

\(\Rightarrow2n+1\inƯ\left(4\right)=\left\{\pm1;\pm2;\pm4\right\}\)

......  tự lm