(m-5)x^2+2（m-5)x+1=0x^2+2x+1/（m-5)=0x^2+2x+1-1+1/（m-5)=0(x+1)^2-(m-6)/（m-5)=0{x+1-√[(m-6)/（m-5)]}{x+1+√[(m-6)/（m-5)]}=0x=√[(m-6)/（m-5)]-1或x=√[(m-6)/（m-5)]-1