Toán Lớp 6: Help me Tìm x,y thuộc Z biết: (3x+2).(y-8)=12 (5x-4).(y+3)=-18

Question

Toán Lớp 6:  Help me  Tìm x,y thuộc Z biết: (3x+2).(y-8)=12 (5x-4).(y+3)=-18

bichhhathu · Answer

ĐK t&igrave;m x;y: x;y &isin; ZZ   a) (3x + 2)(y - 8) = 12   =>  ( left[  begin{array}{l}3x+2=12  y-8=12 end{array}  right. )    =>  ( left[  begin{array}{l}3x = 10  y=12+8 end{array}  right. )    =>  ( left[  begin{array}{l}x=10/3  y=20 end{array}  right. )    Vậy x = 10/3 v&agrave; y = 20 th&igrave; x;y &isin; ZZ   b) (5x - 4)(y + 3) = -18   =>  ( left[  begin{array}{l}5x-4=-18  y+3=-18 end{array}  right. )    =>  ( left[  begin{array}{l}5x=-18+4  y=-18-3 end{array}  right. )    =>  ( left[  begin{array}{l}5x=-14  y=-21 end{array}  right. )    =>  ( left[  begin{array}{l}x=-14/5  y=-21 end{array}  right. )    Vậy x = frac{-14}{5} v&agrave; y = -21 th&igrave; x;y &isin; ZZ

kimnguenoanh · Answer

Giải đáp+Lời giải và giải thích chi tiết:   a)(3x+2)(y-8)=12    TH1:3x+2=12     &rArr;3x=12-2     &rArr;3x=10     &rArr;x=(10)/3     TH2:y-8=12     &rArr;y=12+8     &rArr;y=20     Vậy x=(10)/3 v&agrave; y=20 th&igrave; x;y&isin;Z     b)(5x-4).(y+3)=-18     TH1:5x-4=-18     &rArr;5x=-18+4     &rArr;5x=-14     &rArr;x=-14:5     &rArr;x=(-14)/5     TH2:y+3=-18     &rArr;y=-18-3     &rArr;y=-21     Vậy x=(-14)/5 v&agrave; y=-21 th&igrave; x;y&isin;Z.