一:X^2-8X-16=0,a=1,b=-8,c=-16,b^2-4ac=64-4x1x(-16)=128>0;2分之8正负4又根号8;X1=4+2又根号8或X2=4-2又根号8.二:X^2-8X=16,X^2-8X+16=16+16;(X-4)^2=32;X-4=正负根号32;X1=2又根号8+4或负2又根号8+4.
一:X^2-8X-16=0,a=1,b=-8,c=-16,b^2-4ac=64-4x1x(-16)=128>0;2分之8正负4又根号8;X1=4+2又根号8或X2=4-2又根号8.二:X^2-8X=16,X^2-8X+16=16+16;(X-4)^2=32;X-4=正负根号32;X1=2又根号8+4或负2又根号8+4.