(x-2)(x+6)(x+1)(x+3)=16 (x+4x-12)(x+4x+3)=16 设x+4x=y,则 (y-12)(y+3)=16 y-9y-52=0 y=13或y=-4 当y=13,x+4x=13,x=-2±根号17 当y=-4, x+4x=-4, x=-2
