Vector

Since x is parallel to w
Let x=aw=a(i-j)=ai-aj (where a is a constant)
x is perpendicular to w.
Then y=v-x=(2-a)i+(-3+a)j
Since y is perpendicular to w
y.w=0
[(2-a)i+(-3+a)j].[i-j]=0
2-a+3-a=0
-2a=-5
a=5/2
So x=(5/2)i-(5/2)j
y=(2-a)i+(-3+a)j=(2-5/2)i+(-3+5/2)j=(-1/2)i-(1/2)j

2007-05-11 07:57:25 補充：
x is perpendicular to w.這句copy錯了