Math Problem Statement

Let T : P_3(R)-->P_2(R) be defined by T (f) =f' Find [T]_β

Solution

To find the matrix representation [T]β[T]_{\beta} of the linear transformation TT with respect to a given basis β\beta, we need to proceed with the following steps:

Given:

  • T:P3(R)P2(R)T: P_3(\mathbb{R}) \to P_2(\mathbb{R}) is a linear transformation defined by T(f)=fT(f) = f', where ff' is the derivative of ff.
  • The spaces involved:
    • P3(R)P_3(\mathbb{R}) is the space of polynomials of degree at most 3.
    • P2(R)P_2(\mathbb{R}) is the space of polynomials of degree at most 2.

Standard Basis:

Let’s assume the standard basis for both P3(R)P_3(\mathbb{R}) and P2(R)P_2(\mathbb{R}).

  • The standard basis for P3(R)P_3(\mathbb{R}) is: β={1,x,x2,x3}\beta = \{1, x, x^2, x^3\}

  • The standard basis for P2(R)P_2(\mathbb{R}) is: β={1,x,x2}\beta' = \{1, x, x^2\}

We now need to find the action of T(f)=fT(f) = f' on each element of the basis for P3(R)P_3(\mathbb{R}), then express the result in terms of the basis for P2(R)P_2(\mathbb{R}).

Step 1: Apply TT to the basis elements of P3(R)P_3(\mathbb{R})

  1. T(1)=ddx(1)=0T(1) = \frac{d}{dx}(1) = 0
  2. T(x)=ddx(x)=1T(x) = \frac{d}{dx}(x) = 1
  3. T(x2)=ddx(x2)=2xT(x^2) = \frac{d}{dx}(x^2) = 2x
  4. T(x3)=ddx(x3)=3x2T(x^3) = \frac{d}{dx}(x^3) = 3x^2

Step 2: Express results in terms of the basis for P2(R)P_2(\mathbb{R})

Now, express each result as a linear combination of {1,x,x2}\{1, x, x^2\}:

  1. T(1)=0=01+0x+0x2T(1) = 0 = 0 \cdot 1 + 0 \cdot x + 0 \cdot x^2
  2. T(x)=1=11+0x+0x2T(x) = 1 = 1 \cdot 1 + 0 \cdot x + 0 \cdot x^2
  3. T(x2)=2x=01+2x+0x2T(x^2) = 2x = 0 \cdot 1 + 2 \cdot x + 0 \cdot x^2
  4. T(x3)=3x2=01+0x+3x2T(x^3) = 3x^2 = 0 \cdot 1 + 0 \cdot x + 3 \cdot x^2

Step 3: Construct the matrix [T]β[T]_{\beta}

The columns of the matrix [T]β[T]_{\beta} correspond to the coefficients of the above results in terms of the basis {1,x,x2}\{1, x, x^2\}. So the matrix will be:

0 & 1 & 0 & 0 \\ 0 & 0 & 2 & 0 \\ 0 & 0 & 0 & 3 \end{pmatrix}$$ ### Final Answer: The matrix representation of the transformation $$T$$ with respect to the standard basis $$\beta$$ is: $$[T]_{\beta} = \begin{pmatrix} 0 & 1 & 0 & 0 \\ 0 & 0 & 2 & 0 \\ 0 & 0 & 0 & 3 \end{pmatrix}$$ Would you like further details or have any questions? --- Here are five related questions to explore this concept further: 1. What would happen if $$T$$ were defined as $$T(f) = f + f'$$? 2. How does the matrix representation change for different bases in $$P_3(\mathbb{R})$$ and $$P_2(\mathbb{R})$$? 3. How can we determine the inverse of the matrix $$[T]_{\beta}$$ if it exists? 4. What is the kernel and image of $$T$$ in this case? 5. How do we represent higher-order derivatives in matrix form? **Tip:** Always verify that the dimension of the matrix matches the dimensions of the spaces involved (here, 3x4 for a map from $$P_3$$ to $$P_2$$).

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Math Problem Analysis

Mathematical Concepts

Linear Algebra
Matrix Representation
Polynomial Functions
Derivatives

Formulas

T(f) = f' (derivative of a polynomial)
Matrix representation of a linear transformation

Theorems

Linear transformation between polynomial spaces
Matrix representation with respect to a basis

Suitable Grade Level

College-level Linear Algebra