Để `A=103xy vdots 2; 9`
`*103xy vdots 2=>y=2;4;6;8;0`
`y=0`
`=>1+0+3+x=4+x vdots 9=> x =5`
`y=2`
`=>1+2+3+x=6+x vdots 9=> x=3`
`y=4`
`=>1+3+4+x=8+x vdots 9=> x=1`
`y=6`
`=>1+3+6+x=10+x vdots 9=> x=8`
`y=8`
`=>1+3+8+x=12+x=>x=6`
Vậy `(x=5, y=0); (x=3, y=2); (x=1, y=4); (x=6, y=8) vdots 2;9`
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`B=20xy vdots 5;3`
`20xy vdots 5=> y=0;5`
`y=0`
`=>2+0+x+0=2+x vdots 3=>x=4; 7`
`y=5`
`=>2+0+5+x=7+x vdots 3=>x=2; 5; 8`
Vậy `(x=4,7; y=0); (x=2,5,8; y=5) vdots 5;3`
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`C = 5 x6 y:2,5, 3, 9`
`C = 5 x6 y vdots 2,5=>y=0`
`y=0`
`5+x+6+0= 11+x vdots 3;9=> x=7`
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`D = x25 y vdots 5,3; cancelvdots 9`
`x25y vdots 5=> y=0;5`
`y=0`
`=>x+2+5+0=x+7 vdots 3; cancel vdots 9=> x=5; 8`
`y=5`
`=>x+2+5+5=12+x vdots 3, cancel vdots 9=> x=0; 3; 9`
Vậy `(x=5,8; y=0); (x=0,3,9); (y=5) vdots 3;5; cancel vdots 9`