(x²-2)²-2=xx^4-4x²+4-2-x=0x^4-4x²-x+2=0x²(x²-4)-(x-2)=0x²(x-2)(x+2)-(x-2)=0(x-2)[x²(x+2)-1]=0(x-2)[(x³+x²)+(x²-1)]=0(x-2)[x²(x+1)+(x-1)(x+1)]=0(x-2)(x+1)(x²+x-1)=0所以x=2,或-1,或(-1±√5)/2
3(x+9)=33 x+9=33÷3 x+9=11 x=11-9 x=2