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

Toán Lớp 8: Tìm stn x,y sao cho : `7x – 3xy + 3y = 19`

Tháng Sáu 12, 2022 Toán học 1 Comment 0 views

Toán Lớp 8: Tìm stn x,y sao cho :
7x – 3xy + 3y = 19

Comments ( 1 )

  1. lanhuongthu
    lanhuongthu
    12 Tháng Sáu, 2022 at 9:17 sáng
    Reply
          7x-3xy+3y=19
    => 7x-3xy+3y-19=0
    => (7x-7)-(3xy-3y)-12=0
    => 7(x-1)-3y(x-1)=0+12=12
    => (7-3y)(x-1)=12
    Mà 12=1.12; 2.6; 3.4; 4.3; 6.2; 12.1
    Vậy (7-3y)∈{1; 2; 3; 4; 6; 12}
    => 3y∈{6; 5; 4; 1; -5}
    => y∈{6; 5/3 ; 4/3 ; 1/3 ; -5/3 }
    => (x-1){12; 6; 4; 3; 2; 1}
    => x={13; 7; 5; 4; 3; 2}

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

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