x^3 + x^2 + x = -1/3

a, |x^2 - 5x + 4| > x - 2
b, |3x^2 - 2x - 1 | =< |x^2 - x|
​c, x^3 + x^2 + x = -1/3
e. 1/(x+1) - 2/( x^2-x+1) =< ( 1-2x)/( x^3+1)