Question

化简并求值 5xy的2次方—{2x的2次方y—[3xy的2次方-『4xy的2次方-2xy的2次方』]}其中x=2,y=-1

现在讲啊

Answer 1

5xy的2次方—{2x的2次方y—[3xy的2次方-『4xy的2次方-2xy的2次方』]}
=5xy^2-{2x^2y-[3xy^2-2xy^2]}
=5xy^2-{2x^2y-xy^2}
=5xy^2-2x^2y+xy^2
=6xy^2-2x^2y
=2xy(3y-x)
=2*2*(-1)(3*(-1)-2)
=-4*(-5)
=20
望采纳！

Answer 2

5xy的2次方—{2x的2次方y—[3xy的2次方-『4xy的2次方-2xy的2次方』]}
=5xy^2-{2x^2y-[3xy^2-2xy^2]}
=5xy^2-{2x^2y-xy^2}
=5xy^2-2x^2y+xy^2
=6xy^2-2x^2y
=6*2*1-2*4*(-1)
=12+8
=20

Answer 3

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