3(2x^2y-xy^2)-(4xy^2+3x^2y)其中x=-1y=2

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3(2x^2y-xy^2)-(4xy^2+3x^2y)其中x=-1y=2
3(2x^2y-xy^2)-(4xy^2+3x^2y)其中x=-1y=2

3(2x^2y-xy^2)-(4xy^2+3x^2y)其中x=-1y=2
解由3(2x^2y-xy^2)-(4xy^2+3x^2y)
=6x^2y-3xy^2-4xy^2-3x^2y
=6x^2y-3x^2y-3xy^2-4xy^2
=3x^2y-7xy^2
=3(-1)^2×2-7(-1)×2^2
=6+28
=34

=6x^2y-3xy^2-4xy^2-3x^2y=3x^2y-7xy^2
x=-1, y=2
所以,原式=3*1*2-7*(-1)*4=6+28=34

6x²y-3xy²-4xy²-3x²y
=3x²y-7xy²

将x=-1
y=2代入

=3x1x2-7x-1x4
=6+28
=34

3(2x^2y-xy^2)-(4xy^2+3x^2y)
=6x^2y-3xy^2-4xy^2-3x^2y
=3x^2y-7xy^2
当x=-1y=2时,
原式=3*(-1)^2*2-7*(-1)*2^2
=6+28
=34