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微积分常用公式及运算法则(上册)


0,
π 2
1
lim nn = 1
n→∞
1
lim x x = 1
x→+∞
lim
x→∞
1
+
1 x x
=
e,
lim
x→∞
1

1 x x
=
1 , lim (1+
e x→0
1
x)x
=e
等价无穷小: 当x → 0时, x ∼ sin x ∼ tan x ∼ arcsin x ∼ arctan x ∼ ln(1+ x) ∼ ex −1; 1− cos x ∼ x2 ;(1+ x)a −1 ∼ ax(a ≠ 0);
2!
n!
sin x = x − 1 x3 + 1 x5 −⋯ 3! 5!
柯西中值定理: 若f , g ∈C[a,b],并且f , g ∈ D(a,b),在(a,b)内 g(x) ≠ 0, 那么至少存在一点ξ ∈ (a,b),使 f (b) − f (a) = f ′(ξ ) g(b) − g(a) g′(ξ )
泰勒中值定理:
如果函数f (x)在含x0的某个开区间(a, b) 内具有(n +1)阶导数,即f ∈ Dn+1(a,b),
u v

=
u′v − uv′ v2
设x = ϕ ( y),它的反函数是y = f (x),则有
f
′( x)
=
1 ϕ′( y)
链式求导法则:d y = d y id u dx du dx
对数求导法则:
求幂指函数y = [u(x)]v(x)的导数时,
可先取对数,得 ln y = v(x) ln u(x),
2
2
2 1 + cosα
α tan
=
sin α
= 1− cosα ;
2 1+ cosα sinα
sin

=
2 tanα 1+ tan2 α

cos 2α
=
1− 1+
tan2 α tan2 α

tan 2α = 2 tanα ; sin2 α + cos2 α = 1 1− tan2 α
结合律 (A ∪ B) ∪ C = A ∪ (B ∪ C), (A ∩ B) ∩ C = A ∩ (B ∩ C);
a2
(n)
=
(−1)n n! 2a (x
1 − a)n+1

(x
1 + a)n+1
∑n
(uv)(n) = Cnku(n−k )v(k )
k =0
3
微分定义:
d y = f ′(x)∆x = f ′(x) d x
微分求近似值(线性逼近或一次近似):
∆y ≈ d yx = x0 + ∆x f (x0 + ∆x) ≈ f (x0 ) + f ′(x0 )∆x 令x = x0 + ∆x得, f (x) ≈ f (x0 ) + f ′(x0 )(x − x0 )
=
(−1)n n! x n +1
(ex )(n) = ex
(sin
x)(n)
=
sin
x
+
nπ 2
(cos)(n)
=
cos
x
+
nπ 2
[ln(1 +
x)](n)
=
(−1)(n−1)
(n −1)! (1+ x)n
当x
>
−1
(αu + β v)(n) = αu(n) + β v(n)
x2
1 −
然后两端对x求导,得
y′ = v′(x) ln u(x) + v(x)u′(x)
y
u(x)
参数方程求导:
若对参数方程
x y
= =
ϕ φ
(t) (t)
求导,则有
dy
dy dx
=
d yidt dt dx
=
dt dx
=
φ ′(t ) ϕ ′(t )
dt
高阶导数:
(xn )(n) = n!
1 x
(n)
1+ tan2 α = sec2 α 1+ cot2 α = csc2 α
y = cosh x = ex + e−x ( y > 1) , 2
积化和差:
sin α

cos
β
=
1 2
sin

+
β
)
+
sin


β
)
Байду номын сангаас
cosα
⋅ sin
β
=
1 2
sin

+
β
)

sin (α

β
)
sin α
⋅ sin
β
(xµ )′ = µ xµ −1,
(ax )′ = ax ln a
(ex )′ = ex
(ln x)′ = 1 x
(loga
x)′
=
1 x ln a
(sin x)′ = cos x
(cos x)′ = − sin x
(tan x)′ = sec2 x
(cot x)′ = − csc2 x
(sec x)′ = sec xitan x
那么对于x ∈ (a,b),有
f
(x)
=
f
(x0 ) +
f ′(x0 )(x −
x0 ) +
1 2!
f
′′(x0 )(x −
x0 )2
+⋯+
1 n!
f
(n) (x0 )(x

x0 )n
+
Rn (x)
其中
Rn (x) =
f (n+1) (ξ ) (n +1)!
(
x

x0
)n+1,
Rn (x)称为拉格朗日余项, 这里ξ是x0与x之间的某个值
=
0ab⋯00 ⋯⋯当当mm=<nn ∞⋯⋯当m > n
设 lim u →u0
f
(u)
=
A,
lim
x → x0
u
(
x
)
=
u0
,
且u
(
x)
≠ u0
则 lim f [u(x)] = lim f (u) = A
x → x0
u →u0
重要极限:
lim
x→0
sin x
x
= 1 sin
x
<
x
<
tan
x
x

2
2
sinh(x + y) = sinh x • cosh y + cosh x • sinh y, cosh(x + y) = cosh x • cosh y + sinh x • sinh y, sinh(x − y) = sinh x • cosh y − cosh x • sinh y, cosh(x − y) = cosh x • cosh y − sinh x • sinh y
分配律 A ∩ (B ∪ C) = ( A ∩ B) ∪ (A ∩ C), A ∪ (B ∩ C) = ( A ∪ B) ∩ (A ∪ C); ( A ∪ B)c = Ac ∩ Bc ,
对偶律
( A ∩ B)c = Ac ∪ Bc ;
初等函数:
双曲正弦、余弦、正切及运算
y = sinh x = ex − e−x (−∞ < y < +∞) , 2
f (x) =
f
(x0 ) +
f ′(x0 )(x − x0 ) +
1 2!
f ′′(x0 )(x − x0 )2
+⋯+
1 n!
f
(n)
(x0 )(x

x0 )n
+
o((x

x0 )n ).
常见的基本初等函数的带有佩亚诺余项的麦 克劳林公式:
ex = 1+ x + 1 x2 +⋯+ 1 xn + o(xn )
常用一次近似式: ex ≈ x +1; sin x ≈ x; tan x ≈ x; (1+ x)a ≈ 1+ ax; ln(1+ x) ≈ x;
拉格朗日定理: 若f (x) ∈ C[a, b],并且f ∈ D(a,b), 那么至少存在一点ξ ∈ (a,b),使 f (b) − f (a) = f ′(ξ )(b − a)
微积分常用公式及运算法则
常用三角公式: sin 2α = 2sinα cosα ;
cos 2α = cos2 α − sin2 α = 2 cos2 −1 = 1− 2sin2 α
tan 2α
=
2 tanα 1− tan2 a
; sin 2
α 2
=
1− cosα 2

cos2 α = 1 + cosα ; tan 2 α = 1 − cosα ;
sinh 2x = 2sinh x • cosh x, cosh 2x = cosh2 x + sinh2 x, cosh2 x − sinh2 x = 1.
集合的并、交、余运算律: 交换律 A ∪ B = B ∪ A, A ∩ B = B ∩ A;
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