Question

Answer 1

`a, A = (x+5)^2 >= 0`.

Dấu bằng xảy ra `<=> x = -5.`

`b, B = 2(x^2-3x+5) = 2(x^2 - 3x + 9/4 + 2,75) =2(x-3/2)^2 + 5,5 >= 5,5`

Dấu bằng xảy ra `<=> x=3/2`

Answer 2

`c, 3(x^2 + 1/3x - 1/3)`

`= 3(x^2 + 1/3x + 1/36 - 13/36)`

`= 3(x+1/6)^2 - 13/12 >= -13/12`

Dấu bằng xảy ra `<=> x = -1/6`