Toán Lớp 8: B=x^2-2x+y^2+4y+2026
cứ mình với:(((((((((((((mình cảm ơnnnnn
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Toán Lớp 8: B=x^2-2x+y^2+4y+2026
cứ mình với:(((((((((((((mình cảm ơnnnnn
Comments ( 2 )
$⇔B=x^2-2x+1y^2+4y+4+2021$
$⇔B=(x-1)^2+(y+2)^2+2021$
Vì $(x-1)^2\geq0$
$(y+2)^2+\geq0$
$⇒B=(x-1)^2+(y+2)^2+2021\geq2021$
Dấu $”=”$ xảy ra $⇔$$\left \{ {{(x-1)^2=0} \atop {(y+2)^2=0}} \right.$ $⇔$$\left \{ {{x-1=0} \atop {y+2=0}} \right.$ $⇔$$\left \{ {{x=1} \atop {y=-2}} \right.$
$VẬY$ $min$ $B=2021⇔\left \{ {{x=1} \atop {y=-2}} \right.$