Toán Lớp 6: a)(2x+1).(3y-2)=-55 b)xy-3x-2y=11 c)xy+3x-7y=21 nhanh nhé e sẽ cho ctlhn ạ e cảm ơn nhiều..

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Toán Lớp 6:  a)(2x+1).(3y-2)=-55 b)xy-3x-2y=11 c)xy+3x-7y=21          nhanh nhé e sẽ cho ctlhn ạ   e cảm ơn nhiều..

truonganhthi · Answer

Giải đáp:   ta c&oacute;: ( 2x + 1 ) ( 3y - 2 ) = -55   => 2x + 1 v&agrave; 3y - 2       &isin;     &isin;   Ư(55) = { -55 ; -11 ; -5 ; -1 ; 1 ; 5 ; 11 ; 55 }   v&igrave; 3y - 2 : 3 dư 1 => 3y - 2       &isin;     &isin;   { -11 ; -5 ; 1 ; 55 }   Ta c&oacute; bảng gi&aacute; trị:   2x + 1511-55-13y - 2-11-51552x410-56-23y-9-3357x25-28-1y-3-1119   Vậy c&oacute; 4 cặp cặp x,y cần t&igrave;m c&oacute; trong bảng.   Lời giải và giải thích chi tiết:    b)         x    y    +    3    x    &minus;    2    y    =    11     a)xy+3x&minus;2y=11            &hArr;    x    y    +    3    x    &minus;    2    y    &minus;    6    =    5     &hArr;xy+3x&minus;2y&minus;6=5            &hArr;    x     (     y    +    3     )     &minus;    2     (     y    +    3     )     =    5     &hArr;x(y+3)&minus;2(y+3)=5            &hArr;     (     y    +    3     )      (     x    &minus;    2     )     =    5     &hArr;(y+3)(x&minus;2)=5            &hArr;     hept       {         y    +    3    =    &minus;    1          x    &minus;    2    =    &minus;    5              &hArr;     hept       {         y    =    &minus;    4          x    =    &minus;    3               &hArr; hept{y+3=&minus;1x&minus;2=&minus;5&hArr; hept{y=&minus;4x=&minus;3            &hArr;     hept       {         y    +    3    =    1          x    &minus;    2    =    5              &hArr;     hept       {         y    =    &minus;    2          x    =    7               &hArr; hept{y+3=1x&minus;2=5&hArr; hept{y=&minus;2x=7            &hArr;     hept       {         y    +    3    =    &minus;    5          x    &minus;    2    =    &minus;    1              &hArr;     hept       {         y    =    &minus;    8          x    =    1               &hArr; hept{y+3=&minus;5x&minus;2=&minus;1&hArr; hept{y=&minus;8x=1            &hArr;     hept       {         y    +    3    =    5          x    &minus;    2    =    1              &hArr;     hept       {         y    =    2          x    =