Question

tìm x thuộc Z sao cho:

x mũ 2 + 2x - 7 chia hết cho x + 2

Answer 1

$x^2+2x-7⋮x+2$

=> x(x + 2 ) - 7 ⋮ x + 2

=> 7 ⋮ x + 2

=> x + 2 ∈ {1 ; 7 ; -1 ; - 7}

=> x ∈ {-1;5;-3;-9}

Answer 2

=x (x+2) -7  ⋮  x +2 ;=7 ⋮ x+2; = x+2  ∈ \(x^2+2x-7⋮x+2;=x\left(x+2\right)-7⋮x+2;=7⋮x+2;=x+2\in\left\{1;7;-1;-7\right\};=x\in\left\{-1;5;-3;-9\right\}\)

Answer 3

=x (x+2) -7  ⋮  x +2 ;=7 ⋮ x+2; = x+2  ∈ x^2+2x-7⋮x+2;=x\left(x+2\right)-7⋮x+2;=7⋮x+2;=x+2\in\left\{1;7;-1;-7\right\};=x\in\left\{-1;5;-3;-9\right\}x2+2x−7⋮x+2;=x(x+2)−7⋮x+2;=7⋮x+2;=x+2∈{1;7;−1;−7};=x∈{−1;5;−3;−9}