1. .
1. [a,b] .
2. .
2. .
3. , .
37. .
. = φ(t) . T = {α; β}. f(x) [a; b] = [x(α); x(β)]. ∫f(x)dx (a; b) = ∫f(φ(t))*φ(t)dt (α; β)
. U(x) V(x) . [a; b]. : ∫UdV = UV|ab - ∫VdU
: .
38. . -.
. f(x) [a; b], (- [a; b] () = ∫f(t)dt (a; x), . .
. f(x) [a; b], Ԓ(x) = (∫f(t)dt) (a; x) = f(x), (- [a; b]
-. f(x) [a; b], F(x) , :
∫f(x)dx = F(x)|ab = F(b) F(a)
39. 1- 2- . . .
. : ) [a; b] ; ) f(x) . . , , .. ∫f(x)dx , =-∞ b=+∞ ( .)
/ . f(x) [a; b] (b>a). I(b) = ∫f(x)dx, . I(b) .
1) ∫f(x)dx (a; +∞) = lim ∫f(x)dx (a;b) (bà+∞) 1 [a; +∞). , . .
2) ∫f(x)dx (-∞; b) = lim ∫f(x)dx (a;b) (aà-∞)
3) ∫f(x)dx (-∞; ∞) = ∫f(x)dx (-∞; c) + ∫f(x)dx (c; +∞) =
. f(x)>0. . ., [a; + ∞)
2 . f(x) [a; b),
|
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xàb ε>0 ∫f(x)dx (a; b-ε). 2
f(x) lim ∫f(x)dx (a; b-ε) (εà0+) = ∫f(x)dx (a; b)
: .
40. . . .
. 1) ∫f(x)dx (a; ∞), b>a, ∫f(x)dx (a; ∞) = ∫f(x)dx (b; a) + ∫f(x)dx (b; ∞)
2) ∫f(x)dx (a; ∞) ∫g(x)dx (a; ∞), ∫(αf(x)+-βg(x))dx (a; ∞), α β=const <M.
.
1) . ∫f(x)dx (a; ∞) ∫g(x)dx (a; ∞), : 0 <= f(x) <=g(x), a <= x <∞. , .
:
b (- (a; +∞) ∫f(x)dx (a; b) <= ∫g(x)dx (a; b). ) bà∞. : lim ∫f(x)dx (a; b) (bà∞). . ) 1 ∫f(x)dx (a; b) (bà∞) ∫g(x)dx (a; b) (bà∞)
2) (?). lim f(x)/g(x) (xà+∞) = A < +∞. f(x) g(x) .
3) ( ). 1) f(x) g(x) a <= x <= ∞; 2) f(x) [a; A] F(A) ; 3) g(x) à∞ , ∫f(x)g(x)dx (a; ∞)
, , .
41. .
1) .
y = f(x) (f(x) >= 0), , x=a, x=b, , S = ∫f(x)dx
2)
ρ=ρ(φ), AOB, OA OB, S = ½ ∫(ρ(φ))2dφ
3) .
S = ∫ψ(t)*φ(t)dt, x = φ(t), y = ψ(t)
42. .
a) , , , y = y(x), y(x) - [a; b], x=a x=b : Vx = ∫f 2(x)dx (a; b)
Vx = ∫f 2(x)*x(y)dy (c; d)
|
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) , y ,
, x = x(y), x(y) -
[; d], y y=c y=d
: Vy = ∫f 2(y)dy (c; d) Vy = ∫x2*y(x)dx
43. .
a) .
[a; b] y=f(x) . è . : l = ∫ 1+(y)2dx
) .
x=x(t), y=y(t), x <= t <= β, :
l = ∫. x2(t)+y2(t)dt, (t1; t2) ,
)
ρ=ρ(φ), φ (- [α; β],
l = ∫ ρ2(φ)+ ρ2(φ)dφ (α; β) .
44.
f (x) [ a, b ] ( ) - .
a b , [ a, b ] .