电子信息与通信工程专业英语期末必考公式大全

二、公式

(1) a2

-b2

=(a+b)(a-b)

a squared minus b squared equals open parenthesis a plus b close parenthesis times open parenthesis a minus b close parenthesis.

(2) x 1

x2(x3 4)

X plus one over the quantity x squared times the quantity x cubed minus four to the two-third power.

(3) 1(1 2 ^ n) n n

2

The limit as n approaches infinity of the quantity one over n squared times one plus two plus to plus n.

(4) 12

a[b (c d)]｝

One half open brace, a open bracket b plus open parenthesis c minus d close parenthesis close bracket close brace.

5

(5) anw

nbnn 1

2pi)

Capital sigma the quantity a sub n

times b sub n times the cosine of n time omega over 2 times pi from n equals one to n equals five.

(6)

an

n 1

Product of all an from n equals one to Infinity. (7) max(a

1

,a

2

,^,a

n

) ,min(a

1

,a

2

,^,an)

Maximum/minimum value of the series

a sub one to a sub n.

n

(8) lim 1 1

n

n e Limit as n approaches infinity of

the quantity of one plus one over n to the nth power equals e. (9) limn

squan , limn

infan

Upper/lower limit of a sub n as n approaches/tends to infinity. (10) y'=-1/xn

y prime equals minus one over x to the nth power.

The first derivative of y with respect to x equals minus one over x to nth power.

(11) d2y2 dx

aeax

2

The second derivative of y with respect to x equals a squared times e to the power of minus a times x.

(12) a

x a

alog|x a| c

The indefinite integral of the quantity a over x minus a with respect to x equals a times the quantity logarithm of the absolute value of x minus a plus c.

(13)

pi/2

dx

01 acosx

The integral from 0 to pi over two of the quantity one over one plus a times

cosine of x with respect to x.

(14)a m/n am

(a>0,m,n均为正整

数)

a to the minus m over n power equals one over the nth root of a to the mth power, where a is greater than zero, and both m and n are positive numbers.

(15) f(x)=1+ln (x-2)

The function of x equals one plus log the quantity x minus 2 to the base e.

(16) sin3x≡3sinx-4sin3

x

The sine of three x is equivalent to three times sine of x minus four times the quantity sine x cubed.

（

17

）

Y(n)=

x(h)h(n k)

k

=x(n)*h(n)

Y open parenthesis n close parenthesis equals capital sigma the

quantity x open parenthesis k close

parenthesis h open parenthesis n minus k close parenthesis from k approaches negative infinity to k approaches positive infinity,equals x open parenthesis n close parenthesis convolution sum h open parenthesis n close parenthesis. （18）

A

dS

A

dv

S

v

The close surface integral of A over

a surface S is equal to the volume integral of the pergence of A over the volume V enclosed by S.

（19）

1. The electric charges are the pergence sources of the electric fields.

2. The magnetics fields are solenoidal fields.

3. Time varying magnetic field produces an electric field.

4. The condition current and the displacement current are the curl sources of the magnetic fields.