Question

Need help with some linear Algebra

Answer 1

Find the projection of v = (14,10.-5) onto the subspace v of R3 spanned by (-1,-4,1) and (-6,5,1)

Answer 2

kind of hard, but you have to find the proyection and then apply the formula, u -1 (u * v / v * v) * u

Answer 3

i was using this formula, (v dot v1)/(v1 dot v1) v1 + (v dot v2)/ (v2 dot v2) v2

Answer 4

but im not anle to get the right answer

Answer 5

thats beause you are not using the right one, hold on i have a pic somewere around..

Answer 6

http://www.vitutor.com/geometry/vec/vector_projection.html

Answer 7

none of them mention subspace spanned in r3

Answer 8

its the same thing, you just have to add the third value..

Answer 9

how would i do that, would i use the formula twice?

Answer 10

indeed, mmm what book are you using. If you are using David Lays linear algebra go to chapter 6.2 !

Answer 11

im using elementary linear algebra howard anton chris rorres

Answer 12

so i would do this [(14,10.-5) dot product (-1,-4,1) /norm(-1,-4,1)] multiplied by (-1,-4,1) and then add [(14,10.-5 dot product (-6,5,1) / norm (-6,5,1) multiplied by (-6,5,1)? or am i using the wrong approach?

Answer 13

Hm. You want the projection of \((14,10,-5)\) onto the subspace spanned by \((-1,-4,1),(-6,5,1)\)? Draw it out: