2(x- 1)+(x+2)≥4

x≥4/3

So x≥4/3

2)-2 & lt； X< in 1

2( 1-x)+(x+2)≥4

sulphur dioxide

3) when x≤-2

2( 1-x)-(x+2)≥4

x≤-4/3

So x≤-2

So the solution set is (-∞, 0]U[4/3,+∞).