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x0

 

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0

 

 

 

 

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f (t)dt = F (b) = F (b) - F (a)

 

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b

 

 

 

 

n

xk

 

 

 

n xk

 

 

 

 

 

 

 

 

 

 

 

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a

 

 

 

k =1 x

k -1

 

 

 

k =1 x

k -1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

n

xk

 

 

 

 

 

 

 

 

 

 

 

n

xk

 

 

 

 

(1)

 

 

 

 

( f (x) - f (xk -1 ))g (x)dx + f (xk -1 ) g (x)dx.

 

 

 

 

 

 

 

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k -1

 

 

 

 

 

 

 

 

 

 

 

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x

k -1

 

 

 

 

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n xk

 

 

 

 

 

 

 

 

 

 

 

 

 

 

n

 

xk

 

 

Sn1 = ( f (x) - f (xk -1 ))g (x)dx, Sn2 = f (xk -1 ) g (x)dx.

 

 

 

 

k =1 x

k -1

 

 

 

 

 

 

 

 

 

 

 

 

 

k =1

 

x

k -1

% # Sn1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

n

xk

 

 

 

 

 

 

 

 

 

 

n

 

xk

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Sn1

=

( f (x) - f (xk -1 ))g (x)dx

£

 

( f (x) - f (xk -1 ))g (x)dx

£

 

 

 

k =1 x

k -1

 

 

 

 

 

 

 

 

 

 

k =1

 

x

k -1

 

 

 

 

 

 

 

 

 

n

xk

 

 

 

 

 

 

 

 

 

 

n

 

xk

 

 

 

 

 

 

 

 

 

 

f (x) - f (xk -1 )

 

 

 

g (x)

 

dx £ C

 

f (x) - f (xk -1 )

 

dx =

 

 

 

 

 

 

 

 

 

 

k =1 x

k -1

 

 

 

 

 

 

 

 

 

 

k =1 x

k -1

 

 

 

 

 

 

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n xk

n xk

C ( f (x) - f (xk -1 ))dx £ C ( f (xk ) - f (xk -1 ))dx =

k =1 x

k -1

k =1 x

k -1

 

 

 

 

n

xk

n

C ( f (xk ) - f (xk -1 )) dx = C ( f (xk ) - f (xk -1 ))

 

Dk

 

=

 

 

k =1

xk -1

k =1

 

 

 

 

 

 

Cb - a ( f (x1 ) - f (x0 ) + f (x2 ) - f (x1 ) +... + f (xn ) - f (xn-1 )) = n

C(b - a)( f (xn ) - f (x0 )) = C(b - a)( f (b) - f (a)) .

n

 

n

. '( + 1 + * + ( # n®¥ # +#(#, )

 

lim Sn

= 0.

n®¥

1

 

** # $ %#

x

G(x) = g (t)dt.

a

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m = min G(x) # M = max G(x).

xÎ[a ,b ] xÎ[ a,b ]

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. (* +# * Sn2 + +#(

n

xk

n

xk

xk -1

 

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k =1

xk -1

k =1

a

a

 

n

f (xk -1 )(G(xk ) - G(xk -1 )) =

k =1

f(x0)G(x1) + f(x1)(G(x2) - G(x1)) + ... + f(xn-1)(G(xn) - G(xn-1)) =

G(x1 )( f (x0 ) - f (x1 )) - G(x2 )( f (x1 ) - f (x2 )) +... + G(xn-1 )( f (xn-2 ) - f (xn-1 )) + G(xn ) f (xn-1 ) =

n-1

G(xk )( f (xk -1 ) - f (xk )) + G(xn ) f (xn-1 ).

k =1

. 0 /* , ) f(xk-1) - f(xk) ³ 0 # f(xn-1) ³ 0 # ) m £ G(x) £ M, * ( )# % # ( / Sn2

n-1

 

n-1

m( f (xk -1 ) - f (xk )) + mf (xk -1 ) £ Sn

£

M ( f (xk -1 ) - f (xk )) + Mf (xk -1 )

k =1

2

k =1

 

# #

m(f(x0) - f(x1) + f(x1) - f(x2) + ... + f(xn-2) - f(xn-1) + f(xn-1)) £ Sn2 £

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) + *# + * +

mf(a) £ Sn2 £ Mf(a).

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m £ Sn2 £ M . f (a)

0+ 6 /* $ (1), " (#, )

b

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m £

a

 

£ M .

 

f (a)

 

 

 

 

 

. " (/ + 1 #" + * + " ( # n®¥, )#

 

 

 

 

b

 

 

m £

( fg )(x)dx

£ M .

a

 

f (a)

3 0 )#

b

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a

 

= m .

 

 

 

 

f (a)

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