Chuong 2. Ham nhieu bien so.ppt

Ch­¬ng 2. Hµm nhiÒu biÕn sè

2.1. C¸c kh¸i niÖm c¬ b¶n:

2.1.1. §Þnh nghÜa hµm nhiÒu biÕn sè:

* §Þnh nghÜa:

u= f(M). x1

; x2

; ; x … n

; D;

D R {(x ;x ;...;x ): x R (i 1,n) } 1 2 n i

n ⊂ = ∈ =

M(x ;x ;....;x ) u f(M) f(x ;x ;....;x )

f : D R

1 2 n

= = 1 2 n

→



R {(x ;x ;...;x ;y) R : y f(x ;x ;....;x )} 1 2 n

n 1

f = 1 2 n ∈ =

+

VÝ dô :

{ }

2 2

2 2

2 2

2

(x;y) f(x;y) 1 x y

2) f : D (x;y): x y 1 R

(x;y) z f(x;y) x y

1) f : R R

= − −

= + ≤ →

= = +

→



