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Ответ:

Объяснение:

A)

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

B)

[tex](2x+y^{2}-5)^{2}=(2x+y^{2}-5)*(2x+y^{2}-5)=\\=4x^{2}+2xy^{2}-10x+2xy^{2}+y^{4}-5y^{2}-10x-5y^{2}+25=\\=4x^{2}+y^{4}+4xy^{2}-20x-10y^{2}+25[/tex]

C)

[tex](3x+2y+4)^{2} =(3x+2y+4)*(3x+2y+4)=\\=9x^{2} +6xy+12x+6xy+4y^{2} +8y+12x+8y+16=\\=9x^{2} +4y^{2} +12xy+24x+16y+16[/tex]