問2次咸數解以下.詳細 thx!

1. y = -x2 – 10x – 7
y = -(x2 + 10x )– 7
y = -[x2 + 10x+ (5)2– (5)2] – 7
y = -(x + 5)2+25– 7
y = -(x + 5)2 + 18
∴y的極大值是18.
2. y = 6x2 + 2x + 1
y = 6(x2 + 2x(1/6) ]+ 1
y = 6[x2 + (1/3)x + (1 / 6)2– (1 / 6)2]+ 1
y = 6(x + 1/6)2–6/36+ 1
y = 6(x + 1/6) – 1 / 6 + 1
y = 6(x + 1/6)2 + 5 / 6
∴y的極小值是5/6.


圖片參考：http://i182.photobucket.com/albums/x4/A_Hepburn_1990/ScreenHunter_02Oct182009.jpg?t=1192709564




圖片參考：http://i182.photobucket.com/albums/x4/A_Hepburn_1990/ScreenHunter_03Oct182011.jpg?t=1192709581

咸數不是數學!!

咸數是指甚麼?

y= -x^2-10x-7
y= 6x^2+2x+1

以上不是咸數!!