x⁴+5x³-2x²-5x+1=(x⁴-x²)+(5x³-5x)-(x²-1)=x²(x²-1)+5x(x²-1)-(x²-1)=(x²-1)(x²+5x-1)=(x+1)(x-1)(x²+5x-1) 没学过根式的话就到这里,学过的话,继续:=(x+1)(x-1)[(x+ 5/2)² -29/4]=(x+1)(x-1)[x+(5+√29)/2][x+(5-√29)/2]