Is T_k a Subspace for Polynomial Coefficients Summing to k?

V1 and V2 have no common elements, V1 and V3 have no common elements, but V2+V3 includes the polynomial x which is in V3 and is not in V1.In summary, the conversation discusses whether certain subspaces of polynomials are closed under scalar multiplication and whether a given statement is true or false for direct sums of subspaces. It is concluded that the statement is false and a counterexample is provided.
  • #1
supercali
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1. Homework Statement
A) let T_k be all polynomials with degree 3 or under such that k is their coefficients sum.
so we can say that exist at least 2 values of k for them T_k is the sub vector space of P_3(x)?
B) this question is about direct sum: Let [tex]V_1,V_2,V_3[/tex] be subvector spaces of V if [tex]V_1 \cap V_2={0}[/tex] and [tex]V_1 \cap V_3={0}[/tex] than [tex]V_1 \cap (V_2+V_3)={0}[/tex]


Homework Equations



A) is this true? am i right? look under for my answer

The Attempt at a Solution



A)i think this statement is false for example for k=2,4 we have T_k polynomials but T_k is not close under scalar multipication...is this right?

B)i infact don't think the statement is true but i couldn't find an exaple to support it
 
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  • #2
For A), k=2 or 4 don't work, you are right. But what if k=0? For B), yes, it's false. Take the space of linear polynomials P_1(x). Let V1 be all multiples of (1+x), V2 be all multiples of 1 and V3 be all multiples of x.
 

FAQ: Is T_k a Subspace for Polynomial Coefficients Summing to k?

What is linear algebra?

Linear algebra is a branch of mathematics that deals with vector spaces and linear transformations. It involves the study of operations such as addition, subtraction, multiplication, and division on vectors and matrices, as well as their properties and applications in various fields such as physics, engineering, and computer science.

What are subspaces in linear algebra?

A subspace is a subset of a vector space that satisfies the three properties of a vector space: closure under addition, closure under scalar multiplication, and contains the zero vector. In other words, a subspace is a smaller vector space contained within a larger one, and it itself is a vector space.

How do you determine if a set is a subspace?

To determine if a set is a subspace, you need to check if it satisfies the three properties of a vector space: closure under addition, closure under scalar multiplication, and contains the zero vector. If all three properties are satisfied, then the set is a subspace. If any of the properties are violated, then the set is not a subspace.

What is the difference between a row space and a column space?

A row space is the set of all linear combinations of the rows of a matrix, while a column space is the set of all linear combinations of the columns of a matrix. In other words, the row space is the span of the rows of a matrix, and the column space is the span of the columns of a matrix.

How is linear algebra used in machine learning?

Linear algebra is used in machine learning for various tasks such as data preprocessing, data manipulation, and model building. Some common applications of linear algebra in machine learning include computing dot products, performing matrix operations, and solving systems of linear equations to optimize machine learning algorithms and make predictions.

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