Question

tim x thuoc N

a,\(21x-1⋮11\)

b,\(5x+1⋮7\) va x la STN lon nhat co 3 chu so

c,\(3x-2⋮11\) va \(100< x< 2017\)

d,\(5⋮\left(x-3\right)\)

e,\(\left(3x+2\right)⋮\left(x+1\right)\)

Answer 1

e (3x+2)\(⋮\) (x+1)

vì (x+1)\(⋮\) (x+1)

=> (3x+3)\(⋮\) (x+1)

=> (3x+2)-(3x+3)\(⋮\) (x+1)

=>(3x+2-3x-3)\(⋮\) (x+1)

=> -1\(⋮\) (x+1)

=> (x+1)\(\in\) Ư(-1)={-1;1}

ta có bảng sau

x+1	-1	1
x	-2	0
	loại	thỏa mãn

vậy x=0