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x•(9 x^3 y)∕(-3 x^2 y)
=(9 x^4 y)/(-3 x^2 y)
=-3 x^(4-2) y^(1-1)
=-3 x^2
[(x+y)^2 -(x-y)^2]∕(-4xy)
=[(x^2+y^2+2xy)-(x^2+y^2-2xy)]/(-4xy)
=[4 xy]/(-4 xy)
=1
x•(9 x^3 y)∕(-3 x^2 y)=9x^4y/(-3x^2y)=(-3)x^(4-2)=-3x^2
[(x+y)^2 -(x-y)^2]∕(-4xy)=(x^2+2xy+y^2-x^2+2xy-y^2)/(-4xy)=4xy/(-4xy)=-1
[(x+y)^2 -(x-y)^2]∕(-4xy)
=[(x^2+y^2+2xy)-(x^2+y^2-2xy)]/(-4xy)
=[4 xy]/(-4 xy)
=-1
(1)x•(9 x^3 y-3xy²)∕(-3 x^2 y)
=(9 x^4 y - 3 xy^2)/(-3 x^2 y)
=-3x^(4-2) y + x^(1-2) y^(2-1)
=-3x^2 y +y/x