（2y－1/3－y）²-1≤1-1 （y-1/3）²-1²≤0 （y-1/3+1）(y-1/3-1)≤0 (y+2/3)(y-4/3)≤0 1/3×1/3×(3y+2)(3y-4)≤0 9×1/3×1/3×(3y+2)(3y-4)≤0×9 (3y+2)(3y-4)≤0
（2y－1/3－y）²-1≤1-1
（y-1/3）²-1²≤0
（y-1/3+1）(y-1/3-1)≤0
(y+2/3)(y-4/3)≤0
1/3×1/3×(3y+2)(3y-4)≤0
9×1/3×1/3×(3y+2)(3y-4)≤0×9
(3y+2)(3y-4)≤0
