Question

当X-y=1时,求代数式x 四次方-xy³-x³y-3x²y+3xy²+y四次方

Answer 1

(x-y)^3=x³--3x²y+3xy²-y³

得 -3x²y+3xy=²(x-y)^3-(x³-y³)

原式=x(x³-y³)+(x-y)^3-(x³-y³)+y(y³-x³)

=(x³-y³)(x-y-1)+(x-y)^3

X-y=1 所以 X-y-1 =0

原式=0+1

=1