Lin. Algebra: Is P2 a subspace of P3

In summary, the problem is asking whether P2, a set of polynomials with degree 2 or less, is a subspace of P3, a set of polynomials with degree 3 or less. The solution provided by the student shows that P2 is closed under scalar addition and multiplication, indicating that it is a subspace of P3. However, the concept may be confusing because R2, a set of 2-dimensional vectors, is not a subspace of R3, a set of 3-dimensional vectors. After seeking clarification, the student found a thread that helped them understand the concept better.
  • #1
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Homework Statement


Simple enough: Is P2 a subspace of P3?


Homework Equations





The Attempt at a Solution


I think it is. All P2's can be written in the form 0x^3 + ax^2 + bx + c. Then, it's easy to see that it's closed under scalar addition and multiplication.

Our professor mentioned that R2 is NOT a subspace of R3, so that's throwing me off here. Anyone?
 
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  • #2
Your solution to the problem looks good (if a little short, and I think you mean "addition and scalar multiplication").

What is R2 and R3 here?
 
  • #3

1. What is a subspace in linear algebra?

A subspace in linear algebra is a subset of a vector space that satisfies all the properties of a vector space. This means that it is closed under addition and scalar multiplication, and contains the zero vector.

2. How do you determine if P2 is a subspace of P3?

To determine if P2 is a subspace of P3, we need to check if it satisfies the three properties of a subspace: closure under addition, closure under scalar multiplication, and containing the zero vector. If P2 satisfies all three properties, then it is a subspace of P3.

3. What is the difference between P2 and P3 in linear algebra?

P2 and P3 refer to different degrees of polynomials. P2 represents all polynomials of degree 2 or lower, while P3 represents all polynomials of degree 3 or lower. This means that P2 is a subset of P3.

4. Can a subspace have a dimension larger than its parent vector space?

No, a subspace cannot have a dimension larger than its parent vector space. This is because a subspace is a subset of a vector space, and therefore, its dimension is limited by the dimension of the parent vector space.

5. How can I use the concept of subspaces in real-life applications?

The concept of subspaces is widely used in fields such as physics, engineering, and computer science. It is used to model and solve problems involving multiple variables and equations, such as in systems of linear equations. Subspaces are also crucial in machine learning and data analysis, where they are used to represent and manipulate large datasets.

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