Question

已知xy的2次方等于-3，求-xy（x的3次方乘以y的7次方-3x的2次方乘以y的5次方-y）的值

Answer 1

xy^2=-3-xy（x的3次方乘以y的7次方-3x的2次方乘以y的5次方-y）=-xy(x^3y^7-3x^2y^5-y)=-xy^2(x^3y^6-3x^2y^4-1)=3[(xy^2)^3-3(xy^2)^2-1]=3(-27-27-1)=-165

Answer 2

-xy(x^3*y^7-3x^2*y^5-y)=-x^4y^8+3x^3y^6+xy^2=-(xy^2)^4+3(xy^2)^3+xy^2=-(-3)^4+3(-3)^3+(-3)=-81-81-3=-165