Multivariable Calculus · free preview

Vectors and Geometry in n Dimensions

Vectors in n-dimensional space with componentwise algebra, the dot product, length and angle beyond three dimensions, and matrices as arrays of vectors.

1. n-tuples extend the vector toolkit to any number of dimensions

n-tuples extend the vector toolkit to any number of dimensions

2. The dot product, length and angle generalize by formula

The dot product, length and angle generalize by formula

3. Matrices arrange vectors in a grid

Matrices arrange vectors in a grid

4. Determinants package signed area and volume algebraically

Determinants package signed area and volume algebraically

5. A dot product in five dimensions

Let a=(1,2,−1,3,0)\mathbf{a} = (1, 2, -1, 3, 0) and b=(2,−1,4,1,5)\mathbf{b} = (2, -1, 4, 1, 5) in R5\mathbb{R}^5. What is a⋅b\mathbf{a} \cdot \mathbf{b}?

6. Length of a vector in four dimensions

Let a=(1,−2,2,4)\mathbf{a} = (1, -2, 2, 4) in R4\mathbb{R}^4. What is the length ∥a∥\|\mathbf{a}\|?

7. A matrix-vector product as stacked dot products

Let A=(1234)A = \begin{pmatrix} 1 & 2 \\ 3 & 4 \end{pmatrix} and x=(1,1)\mathbf{x} = (1, 1). What is the product AxA\mathbf{x}?

8. The Cauchy-Schwarz guarantee in every dimension

Which statement about the Cauchy-Schwarz inequality holds for vectors in Rn\mathbb{R}^n?

9. An orthogonal pair in four dimensions

Find the value of kk that makes (1,−2,3,k)(1, -2, 3, k) orthogonal to (2,1,−1,1)(2, 1, -1, 1) in R4\mathbb{R}^4. Give just the number.

10. Distance in four dimensions

Compute the distance between the points (1,0,2,3)(1, 0, 2, 3) and (4,4,2,3)(4, 4, 2, 3) in R4\mathbb{R}^4. Give the exact value as a number or like sqrt(5).

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