Toán Lớp 7: x/4=y/6 va x*y=24
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Toán Lớp 7: x/4=y/6 va x*y=24
giupppppppppppp
Comments ( 2 )
->x*y=4k*6k=24k^2
Mà x*y=24->k^2=1->k=+-1
+)k=1->x=4; y=6
+)k=-1->x=-4; y=-6
Vậy : …
{(x/4=k=>x=4k),(y/6=k=>y=6k):}
Lại có:
xy=24
=>4k.6k=24
=>24k^2=24
=>k^2=24:24
=>k^2=1
=>k^2=(+-1)^2
=>k=+-1
TH1:k=1
{(x=4k=4.1=4),(y=6k=6.1=6):}
TH2:k=-1
{(x=4k=4.(-1)=-4),(y=6k=6.(-1)=-6):}
Vậy (x;y)={(4;6);(-4;-6)}