(1)若x-y-z=3,yz-xy-xz=3,则x^2+y^2+z^2=多少?(2)x^2+x+1/x^2+1/x-4=(1/x+x+?)(1/x+x-?)(3)因式分解:4m^3+m-1(4)已知x^2-x-1=0,求x^5-x^4-3x^3+3x^2+x的值(5)a^2-9x^2+6xy-y^2/(a+3x)^2-(ay+3xy)=1,求证y=6x.

Question

(1)若x-y-z=3,yz-xy-xz=3,则x^2+y^2+z^2=多少?
(2)x^2+x+1/x^2+1/x-4=(1/x+x+?)(1/x+x-?)
(3)因式分解:4m^3+m-1
(4)已知x^2-x-1=0,求x^5-x^4-3x^3+3x^2+x的值
(5)a^2-9x^2+6xy-y^2/(a+3x)^2-(ay+3xy)=1,求证y=6x.

Answer 1

1.9=(x-y-z)^2=x^2+y^2+z^2-2xy-2xz+2yz=x^2+y^2+z^2+6
所以：x^2+y^2+z^2=3
2.x^2+x+1/x^2+1/x-4=(x+1/x)^2+x+1/x-6=(1/x+x+3)(1/x+x-2)
3.=(2m-1)(2m^2+m+1)
4.x^5-x^4-3x^3+3x^2+x=(x^2-x-1)*x^3-2x^3+3x^2+x
太多了啊,不想做了,下次搞少点,我继续给你答.