( , 0 (,) . .
(/=) , = ( ) (/=)=f(x). y=f(x) . y=f(x) y=kx+b, .. k,b , y=kx+b y=f(x). y=kx+b , . 1=kx1+b Þ 21= (y1-(kx1+b))2 (1,1) y=kx+b 22= (y2-(kx2+b))2 .. , y=kx+b =åni=1E2i. =(,b) . *,b*, .
(,b)= åni=1(yi-(kxi+b))2 . D/D=0; D/Db=0
D/D=åni=12(yi-(kxi+b))(-i)=0
kåni=1 i2+båni=1 i =åni=1 i yi;
D/Db=åni=12(yi-(kxi+b))(-1)=0
åni=1 yi -kåni=1 i-nb=0.
íì kåni=1 i2+båni=1 i =åni=1 i yi
î kåni=1 i+nb=åni=1 yi
c b.
12. Rn .
Rn a, b Î Rn
(t)= (1-t) a + t b,
t [0; 1]. a, b [ a, b ]. [ a, b ] Rn, = a + bb, a,b - , a+b=1. Ì Rn , a, bÎ [ a, b ]. n f (), ÌRn, , a, b Î a,bÎ[0; 1] , a+b=1,
f (a + bb) ≤ a f () + b f (b)
, , :
1) f ;
4 . . , f (a + bb) ≤ a f () + b f (b) a, b α,β ≥0 , α+β=1.
f . () , f () , ..
f (a + bb) ≥ a f () + b f (b)
f(x)=(c,x)+c0 , .
.
1. Ì Rn , f ={(,):Î, ≥ f (x)} ( Rn+1) f (x).
2. f (x) , α f (x) α>0 α<0.
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3. f (x) , Uf (α)={: f (x) ≤ α} α. ( ).
4. Ì Rn , , .
5. Ì Rn , i=1,2,k l i(x) n , fi (t) , l i(). F()=f1 (l 1(x))++ f (l (x)) . , fi (t) (l 1()++ l ()), F() .
6. f Ì Rn , φ(t) f () ÌR, F()= φ(f(x)) . f (x) , F() .
7. f (x) Ì Rn , (grad f (a), b-a) ≤ f (b)- f (a) a,bÎ
8. f (x) , [ a, b ]ÌR (a, b). f (x) [ a, b ] f˝ (x)≥0 tÎ (a, b). f (x) f˝ (x)≠0 , (a, b).
9. D Rn, f (x)= f (x1,,n) , D . Î D
C=Cij(X). f (x) D, Î D
∆1=11>0, , ∆n=det c>0
.
1. * - () () f (x) Ì Rn f (x*) () f (x) . f (x) (), * - .
2. f (x) () Ì Rn grad f (x*)=0. * - () f (x) .