In linear algebra, a vector refers to an ordered array of n real numbers called an n-dimensional vector. Generally, it is expressed by Greek letters such as α, β and γ, and sometimes by Latin letters such as A, B, C, O, U, V, X and Y. 。

α=(a 1, a2, …, an) is called n-dimensional vector, where ai is called the i-th component of vector α.

("1" of "a 1" is the subscript of A, "I" of "ai" is the subscript of A, and so on).

Vector addition:

AB+BC=AC

Let a=(x, y)

b=(x '，y ')

Then a+b=(x+x', y+y')

The addition of vectors satisfies parallelogram rule and triangle rule.

Properties of vector addition:

Exchange method:

a+b=b+a

Association rule:

(a+b)+c=a+(b+c)

a+0=0+a=a