Question

1) Tim cac so nguyen n sao cho:

a) n+1 la boi cua n-5

b) 3n-5 chia het cho n-3

c) n²-5 la uoc cua n²-9

 

Answer 1

a)n+1 là bội của n-5

=>n+1 chia hết n-5

<=>(n-5)+6 chia hết n-5

=> 6 chia hết n-5

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

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

Answer 2

b)<=>3(n-3)-2 chia hết n-3

=>6 chia hết n-3

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

=>n\(\in\){2,1,0,-3,4,5,6,9}

Answer 3

<=>(n^2-9)+14 chia hết n^2-9

=>14 chia hết n^2-9

=>n^-9\(\in\){-1,-2,-7,-14,1,2,7,14}
=>n\(\in\){-8,-5,5,187}