# Homework Help: Linear Algebra: Projection onto a subspace

1. Aug 1, 2010

### Kisa30

1. The problem statement, all variables and given/known data

That is the question. The answer on the bottom is incorrect

2. Relevant equations

I believe that is the formula that is supposed to be used.

3. The attempt at a solution

All I really did was plug in the equation into the formula but there is something I am missing because the answer is incorrect

Projection = (41/65)v1 + (26/5)v2
This is what I got after inserting the projection formula.
And in the first image, on the bottom it shows the final solutions I got.

2. Aug 1, 2010

### Villhelm

Just a thought, but do you have to provide the solutions in a specific number format (i.e. rounded to a certain number of figures) or maybe as exact fractions?

3. Aug 1, 2010

### Kisa30

I don't think it's important, no. =)

4. Aug 1, 2010

### vela

Staff Emeritus
What conditions must v1 and v2 meet so that the formula can be used?

An alternative approach would be to find a vector x that's perpendicular to V, and find the projection of v onto x, and subtract that from v. What's left over will lie in the subspace V.

5. Aug 2, 2010

### Kisa30

Apparently the problem is that it's not orthogonal.