Question

tim cac gia tri nguyen cua n de phan so A=3.n+2/n-1 co gia tri la so nguyen

Answer 1

Ta có:

\(A=\dfrac{3n+2}{n-1}=\dfrac{3\left(n-1\right)+5}{n-1}=\dfrac{3\left(n-1\right)}{n-1}+\dfrac{5}{n-1}\)

Để \(A\in Z\) thì \(5⋮n-1\) hay \(n-1\in U\left(5\right)=\left\{\pm1;\pm5\right\}\)

Lập bảng giá trị:

\(n-1\)	\(1\)	\(-1\)	\(5\)	\(-5\)
\(n\)	\(2\)	\(0\)	\(6\)	\(-4\)

Answer 2

A=\(\dfrac{3.n+2}{n-1}=\dfrac{3\left(n-1\right)+5}{n-1}=\dfrac{3\left(n-1\right)}{n-1}+\dfrac{5}{n-1}=3+\dfrac{5}{n-1}\)

Để A nguyên thì 5\(⋮\)n-1 hay n-1\(\in\)Ư(5)

Ta có bảng sau:

n-1	1	5	-1	-5
n	2	6	0	-4

Vậy n\(\in\){2;6;0;-4}

Answer 3

ai nhanh to tick cho

nhung nho phai lam dung nhe!