a:=>6 chia hết cho x
hay \(x\in\left\{1;2;3;6\right\}\)
b: =>9 chia hết cho x
hay \(x\in\left\{1;3;9\right\}\)
c: =>x+1+7 chia hết cho x+1
=>\(x+1\in\left\{1;7\right\}\)
hay \(x\in\left\{0;6\right\}\)
d: =>5 chia hết cho x
hay \(x\in\left\{1;5\right\}\)