x^4+y^4=50 x^2y-xy^2=-14 求代数式x^4- y^4+3xy^2-xy^2-5x^2y+3x^2y-2y^4的值
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![x^4+y^4=50 x^2y-xy^2=-14 求代数式x^4- y^4+3xy^2-xy^2-5x^2y+3x^2y-2y^4的值](/uploads/image/z/173175-15-5.jpg?t=x%5E4%2By%5E4%3D50+x%5E2y-xy%5E2%3D-14+%E6%B1%82%E4%BB%A3%E6%95%B0%E5%BC%8Fx%5E4-+y%5E4%2B3xy%5E2-xy%5E2-5x%5E2y%2B3x%5E2y-2y%5E4%E7%9A%84%E5%80%BC)
x^4+y^4=50 x^2y-xy^2=-14 求代数式x^4- y^4+3xy^2-xy^2-5x^2y+3x^2y-2y^4的值
x^4+y^4=50 x^2y-xy^2=-14 求代数式x^4- y^4+3xy^2-xy^2-5x^2y+3x^2y-2y^4的值
x^4+y^4=50 x^2y-xy^2=-14 求代数式x^4- y^4+3xy^2-xy^2-5x^2y+3x^2y-2y^4的值
题有错吧.因该是+2y^4吧
x^4- y^4+3xy^2-xy^2-5x^2y+3x^2y+2y^4
=x^4+ y^4+2xy^2-2x^2y
=50-2*(-14)
=78
-14=x^2y-xy^2=xy(x-y)
x^4- y^4+3xy^2-xy^2-5x^2y+3x^2y-2y^4
=x^4-3y^4+2xy^2-2x^2y
=x^4-3y^4-2xy(x-y)
题目最后一项会不会是+2y^4?
这样,上式=x^4+y^4-2xy(x-y)=50-2*(-14)=78
x^4- y^4+3xy^2-xy^2-5x^2y+3x^2y+2y^4
=x^4+ y^4+2xy^2-2x^2y
=50-2*(-14)
=78