[tex]\displaystyle\bf\\(3x^{2} +y^{2} )^{2}-x^{2} \cdot(y-x)(x+y)=\\\\=(3x^{2} )^{2} +2\cdot 3x^{2} \cdot y^{2} +(y^{2} )^{2} -x^{2} \cdot(y^{2}-x^{2} )=\\\\=9x^{4} +6x^{2} y^{2} +y^{4} -x^{2} y^{2} +x^{4} =10x^{4}+5x^{2} y^{2} +y^{4}[/tex]

Ответ:

[tex]10x^4 + 5x^2y^2 + y^4[/tex]

Объяснение:

[tex](3x^2+y^2)^2-x^2\cdot(y-x)(x+y)=\\\\3(x^2)^2+2\cdot 3x^2\cdot y^2+(y^2)^2-x^2(y-x)(y+2)=\\\\9x^4+6x^2xy^2+y^4-x^2(y^2-x^2)=\\\\9x^4+6x^2y^2+y^4-x^2y^2+x^4=\\\\10x^4 + 5x^2y^2 + y^4[/tex]