Đáp án:
Ta có
` |-x +8| \ge 0`
`=> |-x +8| - 21 \ge -21`
` => A_{min} = -21` khi ` -x +8 = 0 => x =8`
---------
Ta có
` |-x -17| \ge 0 ; |y-36| \ ge 0`
` =>B \ge 12`
` => B_{min} = 12;` khi ` -x -17 = 0 ; y -36 = 0`
` => x = 17 ; y = 36`
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`c)`
` |2x-8| \ge 0`
` => - |2x-8| \le 0`
` => - |-2x -8| -35 \ le -35`
` => C_{max} = -35`
` 2x -8 =0 => x = 4`
----------------------------
`d)`
` (3x-12)^2 \ge 0`
` => 3(3x-12)^2 \ ge 0`
` => D \ge -37`
` => D_{min} = -37;` khi ` 3x -12 = 0=> x =4`
-------------------------
` |2x+50| \ge 0`
` => -3|2x+50| \le0`
` => -21 - 3|2x+50| \ le -21`
` => E_{max} = -21` khi ` 2x +50 =0 => x =-25`
------------------
` (x-3)^2 \ge 0`
` |x^2 - 9| \ge 0`
` => G \ge 25`
Dấu = khi ` x -3 = 0 => x =3 ; x^2 -9 = 0 => x =± 3`
` => x =3`
