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Find the standard matrix of the linear transformation from R² to R² that first performs a vertical shear that maps e₁→e₁+3e₂ (but leaves e₂unchanged) and then reflects the result through the x₂axis. Hint: you can use the charts on pages 74 - 76 (Section 1.9) for help. Is this linear transformation, T, above invertible? Why or why not? And, if so, find the standard matrix for T⁻¹

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Final answer:

The standard matrix for the described transformation is a multiplication of the shear transformation matrix and the reflection matrix. Since the determinant is non-zero, the transformation is invertible, and the standard matrix for the inverse transformation is provided.

Step-by-step explanation:

To find the standard matrix of a linear transformation from ℝ² to ℝ² that first performs a vertical shear and then reflects through the x₂ axis, we begin by examining the effect on the basis vectors e₁ and e₂. A vertical shear mapping e₁ to e₁ + 3e₂, while leaving e₂ unchanged, can be represented by the matrix

A =



1 0


3 1



The reflection through the x₂ axis negates the second component of any vector, so its matrix is

B =



1 0


0 -1



The overall transformation is represented by the matrix product BA, which yields

T =




1 0


-3 -1


For invertibility, we check if the determinant of T is non-zero:

det(T) = -(1)(-1) - (0)(-3) = 1 ≠ 0

Since the determinant is non-zero, T is invertible. The inverse of T, T⁻¹, can be found by inverting matrix T:

T⁻¹ =



1 0


3 -1



This matrix T⁻¹ is the standard matrix for the inverse transformation T⁻¹.

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