使用配方法，5x^2-5+x-1=05(x^2-1)+(x-1)=05(x+1)(x-1)+(x-1)=0(x-1)(5x+5+1)=0(x-1)(5x+6)=0x=1或-6/5
5x²+x=65x²+x-6=0（5x+6）（x-1）=0x1=-6/2 x2=1
