We would like to minimize the function f : R 3 R, with values: with the constraint x < 1. Explain precisely how

We would like to minimize the function f : R³  → R, with values:

with the constraint ΙΙxΙΙ_∞ 

f(x) = max (x+x2 min (min(x+2, x2 + 2x-5), X3-6), - (x1 x3) + 2x), 1-X1