Câu hỏi của Drake Z

Question

bài 1 : a) (n+15) chia hết cho (n+2)b) 3.n +17 chia hết cho (n+1)bài 2 : tìm stn P sao cho P+2 và P+4 cùng là stn

Tô Hoài An · Accepted Answer

1. a) $\left(n+15\right)⋮\left(n+2\right)$$\Rightarrow\left[n+15-\left(n+2\right)\right]⋮\left(n+2\right)$$\Rightarrow\left[n+15-n-2\right]⋮\left(n+2\right)$$\Rightarrow13⋮\left(n+2\right)$$\Rightarrow\left(n+2\right)\inƯ_{\left(13\right)}=\left\{\pm1;\pm13\right\}$$\Rightarrow n\in\left\{...\right\}$Câu trả lời: 1. a) $\left(n+15\right)⋮\left(n+2\right)$$\Rightarrow\left[n+15-\left(n+2\right)\right]⋮\left(n+2\right)$$\Rightarrow\left[n+15-n-2\right]⋮\left(n+2\right)$$\Rightarrow13⋮\left(n+2\right)$$\Rightarrow\left(n+2\right)\inƯ_{\left(13\right)}=\left\{\pm1;\pm13\right\}$$\Rightarrow n\in\left\{...\right\}$

Tô Hoài An · Answer

b) $\left(3n+17\right)⋮\left(n+1\right)$$\Rightarrow\left(3n+17\right)⋮3\left(n+1\right)$$\Rightarrow\left(3n+17\right)⋮\left(3n+3\right)$$\Rightarrow\left[\left(3n+17\right)-\left(3n+3\right)\right]⋮\left(n+1\right)$$\Rightarrow\left[3n+17-3n-3\right]⋮\left(n+1\right)$$\Rightarrow14⋮\left(n+1\right)$$\Rightarrow\left(n+1\right)\inƯ_{\left(14\right)}=\left\{\pm1;\pm2;\pm7;\pm14\right\}$$\Rightarrow n\in\left\{...\right\}$Câu trả lời: b) $\left(3n+17\right)⋮\left(n+1\right)$$\Rightarrow\left(3n+17\right)⋮3\left(n+1\right)$$\Rightarrow\left(3n+17\right)⋮\left(3n+3\right)$$\Rightarrow\left[\left(3n+17\right)-\left(3n+3\right)\right]⋮\left(n+1\right)$$\Rightarrow\left[3n+17-3n-3\right]⋮\left(n+1\right)$$\Rightarrow14⋮\left(n+1\right)$$\Rightarrow\left(n+1\right)\inƯ_{\left(14\right)}=\left\{\pm1;\pm2;\pm7;\pm14\right\}$$\Rightarrow n\in\left\{...\right\}$

bímậtnhé · Answer

a, $n+15⋮n+2$$\Rightarrow n+2+13⋮n+2$$\Rightarrow n+2\inƯ\left(13\right)=\left\{\pm1;\pm13\right\}$+ n + 2 = 1 $\Rightarrow$n = -1+ n + 2 = -1 $\Rightarrow$n = -3+ n + 2 = -13 $\Rightarrow$n = -15+ n + 2 = 13 $\Rightarrow$n = 11b, $3n+17⋮n+1$$\Rightarrow3\left(n+1\right)+14⋮n+1$$\Rightarrow n+1\inƯ\left(14\right)=\left\{\pm1;\pm2;\pm7;\pm14\right\}$+ n + 1 = 1$\Rightarrow$n = 0+ n + 1 = -1$\Rightarrow$n = -2+ n + 1 = 2$\Rightarrow$n = 1+ n + 1 = -2$\Rightarrow$n = -3+ n + 1 = 7$\Rightarrow$n = 6+ n + 1 = -7$\Rightarrow$n = -8+ n + 1 = 14$\Rightarrow$n = 13+ n + 1 = -14$\Rightarrow$n = -15Câu trả lời: a, $n+15⋮n+2$$\Rightarrow n+2+13⋮n+2$$\Rightarrow n+2\inƯ\left(13\right)=\left\{\pm1;\pm13\right\}$+ n + 2 = 1 $\Rightarrow$n = -1+ n + 2 = -1 $\Rightarrow$n = -3+ n + 2 = -13 $\Rightarrow$n = -15+ n + 2 = 13 $\Rightarrow$n = 11b, $3n+17⋮n+1$$\Rightarrow3\left(n+1\right)+14⋮n+1$$\Rightarrow n+1\inƯ\left(14\right)=\left\{\pm1;\pm2;\pm7;\pm14\right\}$+ n + 1 = 1$\Rightarrow$n = 0+ n + 1 = -1$\Rightarrow$n = -2+ n + 1 = 2$\Rightarrow$n = 1+ n + 1 = -2$\Rightarrow$n = -3+ n + 1 = 7$\Rightarrow$n = 6+ n + 1 = -7$\Rightarrow$n = -8+ n + 1 = 14$\Rightarrow$n = 13+ n + 1 = -14$\Rightarrow$n = -15

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