Question

在三个整式中x^2+2xy,y^2-3xy,x^2中,请任意选择进行加或减运算

Answer 1

①x^2+2xy,②y^2-3xy,③x^2

①+②=x^2+2xy+y^2-3xy

=(x+y)^2-3xy

①-②=x^2+2xy-y^2+3xy

=x^2+5xy-y^2

①-③=x^2+2xy-x^2=2xy

①+③=x^2+2xy+x^2=2x^2+2xy=2x(x+y)

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