是y分之1吗? y-1/y+1≤0 y²+y-1≤0 y²+y+1/4-1/4-1≤0 (y+1/2)²≤(√5/2)² -√5/2≤y+1/2≤√5/2 -√5/2 -1/2 ≤y≤ √5/2-1/2 且y≠0 还是(y-1)/(y+1)≤0 ∵(y-1)/(y+1)≤0 ∴(y-1)(y+1)≤0 => -1≤y≤1 又∵y+1≠0 => y≠-1 ∴-1。
