可我不会╮(╯▽╰)╭···已知2x-y=1/3,xy=2,求2x^4y^3-x^3y^4的值,

问题描述:

可我不会╮(╯▽╰)╭···
已知2x-y=1/3,xy=2,求2x^4y^3-x^3y^4的值,

2x^4y^3-x^3y^4
=x^3y^3(2x-y)
=xy^3(2x-y)
=2^3(1/3)
=8/3

xy=2
2x^4y^3-x^3y^4
=2*2*2*2x-2*2*2y
=16x-8y
因为 2x-y=1/3
所以16x-8y=8(2x-y)
=8*1/3=8/3

2x-y=1/3
xy=2
2x^4y^3-x^3y^4
=x^3y^3(2x-y)
=(xy)^3(2x-y)
=2^3×1/3
=8/3

2x^4y^3-x^3y^4=(xy)^3*(2x-y)=8/3