Đáp án:
Giải thích các bước giải:
a, 4n-5∵n(∵=dấu chia hết)
Ta có :$\left \{ {{y=4n∵n} \atop {x=4n-5∵n}} \right.$ ⇒5∵n
⇒n∈{1,-1,5,-5}
b,-11∵n-1
Ta có :-11∵n-1
⇒n-1∈{11,-11,1,-1}
⇒n∈{12,-10,2,0}
c,2n-1∈Ư(3n+2)⇒3n+2∈B(2n-1)
Lại có:$\left \{ {{y=3n+2∵2n-1} \atop {x=2n-1∵2n-1}} \right.$⇒$\left \{ {{y=6n+4} \atop {x=6n-3}} \right.$
⇒6n+4-(6n-3)∵2n-1
7∵2n-1
⇒2n-1∈{1,-1,7,-7}
⇒2n∈{2,0,8,-6}
⇒n∈{1,0,4,-3}
d, Ta có :n²-7∈B(n+3)
⇒n²-7∵n+3
⇒n(n+3)-3n-7∵n+3
n(n+3)-3(n+3)-9-7∵n+3
n(n+3)-3(n+3)-16∵n+3
ta có $\left \{ {{y=n(n+3)-3(n+3)∵n+3} \atop {x=n(n+3)-3(n+3)-16∵n+3}} \right.$
⇒16∵n+3
⇒n+3∈{1,-1,2,-2,4,-4,8,-8,16,-16}
⇒n∈{-2,-4,-1,-5,1,-7,5,-13,13,-19}
