Toán Lớp 7: Tìm x,y nguyên biết: |x+3y-1| + 3.|y+2| = 0
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Toán Lớp 7: Tìm x,y nguyên biết: |x+3y-1| + 3.|y+2| = 0
Comments ( 1 )
Giải đáp:
|x+3y-1| + 3.|y+2| = 0
Có |x+3y-1| >= 0 AAx,y
3|y+2| >=0 AAy
-> |x+3y-1| + 3.|y+2| >=0
Dấu ”=” xảy ra
⇔ {(x+3y-1=0),(y+2=0):}
⇔ {(x+3(-2)-1=0),(y=-2):}
⇔ {(x-6-1=0),(y=-2):}
⇔ {(x=7),(y=-2):}
Vậy |x+3y-1| + 3.|y+2| = 0 ⇔ {(x=7),(y=-2):}