Math Problem Statement

Define a linear transformation T: P_2 → ℝ^2 by T(p) = [p(0) p(0)]. Find polynomials p1 and p2 in P_2 that span the kernel of T, and describe the range of T.

Solution

The given problem defines a linear transformation T:P2R2T: P_2 \to \mathbb{R}^2 by the following mapping:

T(p)=[p(0)p(0)]T(p) = \begin{bmatrix} p(0) \\ p(0) \end{bmatrix}

Here, P2P_2 is the space of polynomials of degree at most 2, meaning any polynomial in P2P_2 has the form:

p(x)=ax2+bx+cp(x) = ax^2 + bx + c

1. Finding the Kernel of TT

The kernel of TT, ker(T)\text{ker}(T), consists of all polynomials p(x)P2p(x) \in P_2 such that:

T(p)=[00]T(p) = \begin{bmatrix} 0 \\ 0 \end{bmatrix}

This implies:

p(0)=0p(0) = 0

Substituting x=0x = 0 into p(x)=ax2+bx+cp(x) = ax^2 + bx + c, we get:

p(0)=cp(0) = c

So, for T(p)=0T(p) = 0, we must have c=0c = 0. Thus, the polynomials in the kernel of TT are those of the form:

p(x)=ax2+bxp(x) = ax^2 + bx

The kernel is spanned by the polynomials:

p1(x)=xandp2(x)=x2p_1(x) = x \quad \text{and} \quad p_2(x) = x^2

Thus, the kernel of TT is spanned by {x,x2}\{x, x^2\}.

2. Describing the Range of TT

The range of TT, range(T)\text{range}(T), consists of all vectors of the form [p(0)p(0)]\begin{bmatrix} p(0) \\ p(0) \end{bmatrix}. Since the output vector depends only on the constant term cc of the polynomial p(x)p(x), we have:

T(p)=[cc]T(p) = \begin{bmatrix} c \\ c \end{bmatrix}

Thus, the range of TT is spanned by the vector [11]\begin{bmatrix} 1 \\ 1 \end{bmatrix}. Therefore:

range(T)=span([11])\text{range}(T) = \text{span} \left( \begin{bmatrix} 1 \\ 1 \end{bmatrix} \right)

Conclusion:

  • The kernel of TT is spanned by {x,x2}\{x, x^2\}.
  • The range of TT is spanned by [11]\begin{bmatrix} 1 \\ 1 \end{bmatrix}.

Would you like further details on any part of this problem?


Here are five related questions to deepen your understanding:

  1. How does the rank-nullity theorem apply to this transformation TT?
  2. What is the dimension of the kernel and range of TT?
  3. How would you describe the geometric interpretation of the kernel and range?
  4. Can the transformation TT be represented by a matrix, and if so, what would it look like?
  5. How does changing the definition of TT (e.g., modifying the output components) affect the kernel and range?

Tip: Always check the rank of a linear transformation to understand how many independent vectors map to nonzero outputs.

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Math Problem Analysis

Mathematical Concepts

Linear Transformations
Polynomials
Kernels and Range

Formulas

T(p) = [p(0) p(0)]
p(x) = ax^2 + bx + c
T(p) = 0 implies p(0) = 0

Theorems

Rank-Nullity Theorem

Suitable Grade Level

Undergraduate - Linear Algebra