设正整数n,0求【x】｛x｝<=x-1，我打错了哎,你整我.我做好久哦解:设正整数n, 0<=k<1当a>0时,a=n+k,则[a]=n{a}=k 有nk<=n+k-1有(n-1)(k-1)<=0∴n-1>=0 n>=1当a<0时,a=-n+k则[a]=-n{a}=k有-nk<=-n+k-1∴k>=1矛盾显然,a不等于0故不等式[a]·{a}<=-1的解集是a>=1