（1/2）^log3 (log1/5(x^2-4/5)＜1log3 (log1/5(x^2-4/5)＞0 log1/5(x^2-4/5) ＞1 0＜x^2-4/5 ＜1/5 4/5＜x＜1 2根号5/5＜x＜1 或-1＜x＜-2根号5/5