Toán Lớp 6: Tìm x,y thuộc N biết: a)(2x-1)(2y+1)=2 b)(4x+1)(y-3)=5

Question

Toán Lớp 6:  Tìm x,y thuộc N biết: a)(2x-1)(2y+1)=2 b)(4x+1)(y-3)=5

quynhthanhnhu · Answer

a)(2x-1)(2y+1)=2   &rArr;(2x-1)(2y+2)=1.2=(-1).(-2)=2.1=(-2).(-1)   TH1:(2x-1)(2y+1)=1.2   =>x=1 ; y=1/2 (kTM)   TH2:(2x-1)(2y+1)=(-1).(-2)   =>x=0;y=-3/2(ktm)   TH3:(2x-1)(2y+1)=2.1   =>x=3/2;y=0(ktm)   Vậy(x;y)= Ф   b)(4x+1)(y-3)=5   &rArr;(4x+1)(y-3)=1.5=5.1=(-1)(-5)=(-5).(-1)   Th1:(4x+1)(y-3)=1.5   &rArr;x=0;y=8   th2:(4x+1)(y-3)=5.1   &rArr;x=1;y=4   TH3:(4x+1)(y-3)=(-1)(-5)   &rArr;x=-2/4;y=-2(ktm)   TH4:(4x+1)(y-3)=(-5)(-1)   =>x=-6/4;y=-2(KTM)   vậy (x;y)=(0,8);(1,4)

chauhoangmy98 · Answer

a, (2x-1)(2y+1)=2   Ta c&oacute; bảng:   2x-1              1              -1                 2                -2   2y+1             2              -2                 1                -1   x                   1                0                3/2             -1/2   y                  1/2           -3/2               0               -1   V&igrave; x;y inNN n&ecirc;n:   ->(x;y) in&empty;   Vậy (x;y) in&empty;   b,(4x+1)(y-3)=5   Ta c&oacute; bảng:   4x+1             1                 -1                  5                  -5     y-3                5                 -5                  1                  -1   x                   0                -1/2                1                 -3/2   y                  8                  -2                  4                    2   V&igrave; x;y inNN n&ecirc;n:   ->(x;y) in{(0;8),(1;4)}   Vậy (x;y) in{(0;8),(1;4)}