0x(x+2)=225-20根号a ,-根号a(根号n)-m,(-根号n)-m(1)x+3=正负4 (2)(6x-7)^2=128 (3)x^2=25 x=1,x=-7 6x-7=正负8倍根号2 x=正负5 x=[(正负8倍根号2)+7]/6