西要毛子律技大學XIDIANUNIVERSITY例5判断Pn的下列子集合哪些是子空间：W =((xi,x2,"",xn)x +x2 +..+xn = 0,x, e P)W, =((xi,x2,"",xn)xi +x2 +...+xn =1,x; e P)W, = ((xi,x2,"",xn-1,0)] x, e P,i =1,2,.",n-1)若为Pn的子空间，求出其维数与一组基例5 判断Pn的下列子集合哪些是子空间： 1 1 2 1 2 {( , , , ) 0, } W x x x x x x x P = + + + =  n n i 2 1 2 1 2 {( , , , ) 1, } W x x x x x x x P = + + + =  n n i 3 1 2 1 {( , , , ,0) , 1,2, , 1} W x x x x P i n =  = − n i − 若为Pn的子空间，求出其维数与一组基