Question

bài 7 ạ

Answer 1

7:

Q=-(x^2-6x+10)

=-(x^2-6x+9+1)

=-(x-3)^2-1<=-1<0 với mọi x

Answer 2

`7.`

`Q = 6x - x^2 -10`

`=-(x^2 - 6x + 10)`

`=-(x^2 - 6x + 9 + 1)`

`=-(x^2 - 6x + 9) - 1`

`=-(x-3)^2 - 1`

Do `-(x-3)^2 <= 0`

`=>Q <= -1`

Dấu "`=`" xảy ra `<=>x-3 = 0`

`<=>x = 3`

Vậy `min Q = -1 <=>x=3`