(1) has x0∈R, which makes f(x0)≤m hold.
That is, m≥f(x)min, f (x) min = 2 and m≥2.
(2) Any m ∈ [1, 2] has m? +2m-f(t)≤0.
Then m ∈ [1, 2], f(t)≥(m? +2m) Maximum capacity.
m? +2m=(m+ 1)? - 1,m = 2,(m? +2m) Max =8
F(t)≥8, that is | t+ 1 |+t- 1 | ≥ 8, and the solution is t≥4 or t≤-4.