（x^2-1994^2)^2-7976x-1=0 （x+1994)^2.(x-1994)^2-7976x-1=0 [(x+1994)^2+1][(x-1994)^2-1]=0 得(x+1994)^2+1=0（舍去）或者(x-1994)^2-1=0 (x-1994)^2=1得x=1993或者x=1995