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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 6: Bài 13: Tìm số nguyên x sao cho : a) – 15 chia hết (2x + 1) b) – 121 chia hết (x + 9) c) (2x + 7) chia hết (x + 2) c) (3x + 10) chia

Tháng Tư 19, 2022 Toán học 1 Comment 0 views

Toán Lớp 6: Bài 13: Tìm số nguyên x sao cho :
a) – 15 chia hết (2x + 1)
b) – 121 chia hết (x + 9)
c) (2x + 7) chia hết (x + 2)
c) (3x + 10) chia hết (x + 3)

Comments ( 1 )

  1. haianhtu97
    haianhtu97
    19 Tháng Tư, 2022 at 9:10 chiều
    Reply
    a)-15 \vdots (2x + 1)
    =>2x + 1 \in Ư(-15)
    =>2x + 1 \in {1; -1; 3; -3; 5; -5; 15; -15}
    =>x \in {0 ; -1 ; 1 ; -2 ; 2 ; -3 ; 7 ; -8}
    Vậy x \in {0 ; -1 ; 1 ; -2 ; 2 ; -3 ; 7 ; -8}
    b)-121 \vdots (x + 9)
    =>x + 9 \in Ư(121)
    =>x + 9 \in {1;11;121;-1;-11;-121}
    =>x \in {-8 ; 2 ; 112 ; -10 ; -20 ; -130}
    Vậy x \in {-8 ; 2 ; 112 ; -10 ; -20 ; -130}
    c)(2x + 7) \vdots (x + 2)
    =>2x + 4 + 3 \vdots x + 2
    =>2(x + 2) + 3 \vdots x + 2
    =>3 \vdots x + 2
    =>x + 2 \in Ư(3) = {-3;-1;1;3}
    =>x  \in {-5;-3;-1;1}
    Vậy x \in {-5;-3;-1;1}
    d)(3x + 10) \vdots (x + 3)
    (3x + 10) – (3x + 4) \vdots x + 3
    (3x + 10 – 3x – 4) \vdots x + 3
    6 \vdots x + 3
    =>x + 3 \in Ư(6) = {1;2;3;6;-1;-2;-3;-6}
    =>x \in {-2;-1;0;3;-4;-5;-6;-9}
    Vậy x \in {-2;-1;0;3;-4;-5;-6;-9}

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222-9+11+12:2*14+14 = ? ( )

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