Toán Lớp 6: [2n+5] chia hết n+5 helppppp meeeee
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Toán Lớp 6: [2n+5] chia hết n+5 helppppp meeeee
Comments ( 2 )
~ Bạn tham khảo ~
2n + 5 \vdots n + 5
=> 2n + 10 – 5 \vdots n + 5
=> 2(n+5) – 5 \vdots n + 5
Vì 2(n+5)\vdots n+5
=> 5 \vdots n+5
=> n+ 5 \in Ư(5) = {1;5;-1;-5}
=> n \in {-4;1;-6;-10}
Vậy n \in {-4;1;-6;-10}
$\text{ @HV }$
2n + 5 \vdots n + 5
⇒ 2n + 10 – 5 \vdots n + 5
⇒ 2. (n + 5) – 5 \vdots n + 5
Vì n + 5 \vdots n + 5
⇒ 2. (n + 5) \vdots n + 5
Vậy để ⇒ 2. (n + 5) – 5 \vdots n + 5 ⇒ n + 5 \in Ư(5)
⇒ n + 5 \in {-5 ; -1 ; 1 ; 5}
⇒ n \in {-10 ; -6 ; -4 ; 0}
Vậy n \in {-10 ; -6 ; -4 ; 0} thì 2n + 5 \vdots n + 5