- #1
devonho
- 8
- 0
Homework Statement
Given vectors
[itex]
{\bf r}=\left[r_1,r_2,r_3\ldots{}r_n\right]^T
[/itex]
[itex]
{\bf e}=\left[e_1,e_2,e_3\ldots{}e_n\right]^T
[/itex]
I need to write the sum
[itex]
\sum_{i=1}^{n}r_ie_i^2
[/itex]
in terms of [itex]{\bf r}[/itex] and [itex]{\bf e}[/itex]
Homework Equations
Nil.
The Attempt at a Solution
Without [itex]r_i[/itex], I am able to write [itex]\sum_{i=1}^{n}e_i^2[/itex] as
[itex]
\sum_{i=1}^{n}e_i^2={\bf e}^T{\bf e}
[/itex]
If [itex]r_i[/itex] can be independant of [itex]i[/itex] I should be able to move it out of the summation. I am looking for some expansion/reexpression of [itex]r_i[/itex].