①(x+y+z）（-x+y+z）(x-y+z)(x+y-z)②设x=2分之（根号5-1） 求x四次方+x二次方+2x-1③若x二次方+xy-2y二次方=0 则（x二次方+y二次方）分之（x二次方+3xy+y二次方）=?
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(1)原式=x+y+z)(-x+y+z)(x-y+z)(x+y-z)=[(x+y+z)(x+y-z)]*{[z+(x-y)][z-(x-y)]}=[(x+y)^2-z^2][z^2-(x-y)^2]=(x^2+2xy+y^2-z^2)[z^2-(x-y)^2]=4*x^2*y^2-(x^2+y^2-z^2)^2(2)原式=x^2(x^2+1)+2x-1=(3-√5)/2*[(3-√5)...