[Toán 8] phân tích đa thức thành nhân tử khó

M

mydream_1997

nho cam on minh do:D
[TEX]x^4+y^4+x^2y^2-x^3y-xy^3[/TEX]
[TEX]= x^4 +y^4 + \frac {x^2y^2}{4} -2.x^2.\frac {xy}{2} -2.y^2.\frac {xy}{2} +2.x^2.y^2 -\frac {5}{4}.x^2y^2[/TEX]
[TEX]= (x^2+y^2-xy)^2 -\frac {5}{4}x^2y^2[/TEX]
[TEX]= (x^2 +y^2-xy - \frac {\sqrt {5}}{2}.xy)(x^2+y^2-xy+ \frac {\sqrt {5}}{2}.xy)[/TEX]:D
 
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