已知2x-y=1/4,xy=-2,求2x^5y^4-x^4y^5

已知2x-y=1/4,xy=-2,求2x^5y^4-x^4y^5
已知2x-y=1/4,xy=-2,求2x^5y^4-x^4y^5

已知2x-y=1/4,xy=-2,求2x^5y^4-x^4y^5
2x^5y^4-x^4y^5
=x^4y^4(2x-y)
=(xy)^4(2x-y)
=(-2)^4*1/4
=4

2x^5y^4-x^4y^5=x^4y^4(2x-y)
因为xy=-2所以x^4y^4=（-2）^4=16
原式=16*1/4=4