Question

a)3n+15 chia hết cho n+3
b)n² - 7 chia hết cho n + 1
c)n² - 3n + 7 chia hết cho n - 3d
d)n² - 4n + 7 chia hết cho n - 3
mong mn giúp em giải

Answer 1

a: =>3n+9+6 chia hết cho n+3

=>\(n+3\in\left\{1;-1;2;-2;3;-3;6;-6\right\}\)

hay \(n\in\left\{-2;-4;-1;-5;0;-6;3;-9\right\}\)

b: \(\Leftrightarrow n^2-1-6⋮n+1\)

=>\(n+1\in\left\{1;-1;2;-2;3;-3;6;-6\right\}\)

hay \(n\in\left\{0;-2;1;-3;2;-4;5;-7\right\}\)

c: =>7 chia hết cho n-3

=>\(n-3\in\left\{1;-1;7;-7\right\}\)

hay \(n\in\left\{4;2;10;-4\right\}\)

d: =>n^2-4n+3+4 chia hết cho n-3

=>\(n-3\in\left\{1;-1;2;-2;4;-4\right\}\)

hay \(n\in\left\{4;2;5;1;7;-1\right\}\)