已知x+y=5,则x(x-y)+5y(x+y)+(x^3-3y^2)的值是A.5B.10C.25D.50

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已知x+y=5,则x(x-y)+5y(x+y)+(x^3-3y^2)的值是A.5B.10C.25D.50已知x+y=5,则x(x-y)+5y(x+y)+(x^3-3y^2)的值是A.5B.10C.25

已知x+y=5,则x(x-y)+5y(x+y)+(x^3-3y^2)的值是A.5B.10C.25D.50
已知x+y=5,则x(x-y)+5y(x+y)+(x^3-3y^2)的值是
A.5
B.10
C.25
D.50

已知x+y=5,则x(x-y)+5y(x+y)+(x^3-3y^2)的值是A.5B.10C.25D.50
已知x+y=5,则x(x-y)+5y(x+y)+(x^2-3y^2)的值是
x(x-y)+5y(x+y)+(x^2-3y^2)
= x ^2 - xy + 5xy + 5y^2 + x^2 - 3y^2
= 2x ^2 + 4xy + 2y^2
= 2 ( x+y ) ^2
= 2x 25
= 50
选D

原式=x²-xy+5xy+5y²+x²-3y²
=2x²+4xy+2y²
=2(x+y)²
=2*5²
=50
选D

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