Question

tìm n sao cho

a)n+3 chia hết cho n-1

b)4n+3 chia hết cho 2n+1

 

Answer 1

\(\left(n+3\right)⋮\left(n-1\right)=>\left(n-1\right)+4⋮\left(n-1\right)\\ =>4⋮\left(n-1\right)\\ =>n-1\inƯ\left(4\right)=\left\{\pm1;\pm2;\pm4\right\}\\ =>n\in\left\{0;2;-1;3;-3;5\right\}\)

Answer 2

\(\left(4n+3\right)⋮\left(2n+1\right)=>2\left(2n+1\right)+1⋮\left(2n+1\right)\\ =>1⋮\left(2n+1\right)\\ =>2n+1\inƯ\left(1\right)=\left\{\pm1\right\}\\ =>2n\in\left\{0;-2\right\}\\ =>n\in\left\{0;-1\right\}\)