Ta có
` C = 2|-x+1| -5`
Ta có
` |-x-1| \ge 0`
` => 2|-x-1| \ge 0`
` => 2|-x-1| - 5 \ge -5`
` => C_{min} = -5` khi
` -x + 1 = 0 => x = 1`
*****
Ta có
` (-y-2)^2 \ge 0`
` |3-x| \ge 0`
` => (-y-2)^2 + |3-x| - 4 \ge -4`
` => D_{min} = -4`
Khi ` -y - 2 = 0 => -y = 2 => y =-2`
` 3-x = 0 => x =3`