Question

bai 1:Tim n thuoc Z

a)n-1 chia het cho n+5

b) 3n+2 chia het cho n-1

Answer 1

a)n-1 chia hết cho n+5

=>n+5-6 chia hết cho n+5

=>6 chia hết cho n+5

=>n+5 thuộc Ư(6)={-1;1;-2;2;-3;3;-6;6}

=>n thuộc {-6;-4;-7;-3;-11;1}

b) 3n+2 chia het cho n-1

=>3n-3+5 chia hết cho n-1

=>5 chia hết cho n-1

=>n-1 thuộc Ư(5)={-1;1;-5;5}

=>n thuộc{0;2;-4;6}

 

Answer 2

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Answer 3

a)<=>(n+5)-6 chia hết n+5

=>6 chia hết n+5

=>n+5\(\in\){-1,-2,-3,-6,1,2,3,6}

=>n\(\in\){-6,-7,-8,-11,-4,-3,-2,1}

b)3(n-1)+3 chia hết n-1

=>9 chia hét n-1

=>n-1\(\in\){-1,-,3,-9,1,3,9}

=>n\(\in\){0,-2,-8,2,4,10}