∴f(x)=
(x+5)(x+2) |
x+1 |
x2+7x+10 |
x+1 |
=
(x+1)2+5(x+1)+4 |
x+1 |
=(x+1)+
4 |
x+1 |
=-[(-x-1)+
4 |
−x−1 |
≤-2
(−x−1)•
|
=-4+5=1.
当且仅当-x-1=
4 |
−x−1 |
所以当且仅当x=-3时,f(x)=
(x+5)(x+2) |
x+1 |
(x+5)(x+2) |
x+1 |
(x+5)(x+2) |
x+1 |
x2+7x+10 |
x+1 |
(x+1)2+5(x+1)+4 |
x+1 |
4 |
x+1 |
4 |
−x−1 |
(−x−1)•
|
4 |
−x−1 |
(x+5)(x+2) |
x+1 |