1)v1不是向量空间:
若a=(x1,x2,…,xn〕,b=(y1,y2,...,yn)∈V1
则a+b=(x1+y1,x2+y2,...,xn+yn)∉V1,因为它的元素之和=2≠1,
2)v2是向量空间:
若a=(x1,x2,…,xn〕,b=(y1,y2,...,yn)∈V2
则①a+b=(x1+y1,x2+y2,...,xn+yn),满足(x1+y1)+(x2+y2)+...+(xn+yn)=0,a+b∈V2
②对任意常数λ,λa=〔λx1,λx2,…,λxn〕,满足λx1+λx2+…+λxn=0λa∈V2
基:e1=(1,-1,0,0,...,0)',e2=(1,0,-1,0,.,0),.,e(n-1)=(1,0,0,0,...,-1)
维数=n-1