Proving Inner Product Space: x not in W, y in W(perp)

In summary, if x is a non-zero element not contained in a finite-dimensional subspace W of an inner product space V, it must have a component in W perp. This can be proven using the Gram-Schmidt process, where x is decomposed into a sum of vectors from W and W perp. Therefore, there exists a vector y in W perp such that the dot product of x with y is non-zero.
  • #1
jbear12
13
0
Let V be an inner product space, and let W be a finite-dimensional subspace of V. If x[tex]\notin[/tex] W, prove that there exists y[tex]\in[/tex] V such that y [tex]\in[/tex] W(perp), but <x,y>[tex]\neq[/tex] 0.

I don't have a clue...
Thanks
 
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  • #2
you could start by using something along the lines of gram-schmidt to decompose to x into a sum of vector from W & one from W perp...
 
  • #3
Umm..I don't really get it. Can you explain more specifically? Thank you.
 
  • #4
what don't you get?

first you need to assume x is non-zero

x is not contained in W, and as its non-zero, this means it must have a component in W perp , (as V = W + W perp by defintion of W perp, sloppy notation here, but hopefully you get the idea)

now consider the dot product of x with the component of x in W perp
 

What is an inner product space?

An inner product space is a mathematical concept that refers to a vector space with an additional structure called an inner product. This inner product allows for the definition of concepts such as length, angle, and orthogonality within the vector space.

What is the significance of proving that x is not in the orthogonal complement of W?

Proving that x is not in the orthogonal complement of W means that x is not perpendicular or orthogonal to all vectors in W. This is significant because it helps to define the relationship between x and the subspace W, and can be used to demonstrate properties of the vector space.

What does it mean for y to be in the orthogonal complement of W?

Y being in the orthogonal complement of W means that y is perpendicular or orthogonal to all vectors in W. This implies that y is also perpendicular to the subspace W as a whole, and is a useful concept in analyzing the properties of vector spaces.

How is proving inner product space related to linear algebra?

Proving inner product space is a fundamental concept in linear algebra, as it allows for the definition of important concepts such as orthogonality and angle within vector spaces. This is crucial for understanding and solving problems in linear algebra, as well as in many other fields of mathematics and science.

What are some common techniques used to prove inner product space?

Some common techniques used to prove inner product space include using the properties and axioms of inner products, applying the definition of orthogonality, and using mathematical induction. Other techniques may also be used depending on the specific problem at hand.

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