(1) (x+1)^2+4(x+1)=0 (提取公因式)(x+1)(x+1+4)=0(x+1)(x+5)=0x1=-1,x2=-5.(2) (5x-1)^2-5=0 (运用平方差公式)(5x-1+√5)(5x-1-√5)=0x1=(1-√5)/5 ,x2=(1+√5)/5(3)x^2+5x+4=0 (十字相乘)(x+1)(x+4)=0x1=-1,x2=-4...