Đáp án:
`a)`
Ta có
` (5x-2)^2 \geq 0`
` => (5x-2)^2 +100 \geq 100`
` => min = 100` khi ` 5x -2 = 0`
` => 5x = 2`
`b)` Ta có
` (2x+1)^4 \geq 0`
` => (2x+1)^4 - 99 \geq -99`
` => min = -99` khi ` 2x + 1 = 0`
` => x = -1/2`
`c)`
` (x-36)^2 \geq 0`
` |y-5| \geq 0`
` => (x-36)^2 + |y-5| + 2013 \geq 2013`
` => min = 2013` khi
` x -36 = 0 ; y -5 = 0`
` => x = 36 ; y =5`