解；4x^2+8x+4=0,4（x^2+2x+1）=0,4（x+1）^2=0,（x+1）^2=0,x+1=0,x=-1,x1=x2=-1。
4x²+8x=-44x²+8x+4=04(x²+2x+1)=04(x+1)²=0x+1=0=>x=-1
4x^2+8x=-4x^2+2x+1=0(x+1)^2=0x=-1
