Math Problem Statement

For the vectors u = (-5, 1) and v = (-3, 2), calculate proj_u v and scal_u v.

Solution

The problem is asking for the projection and scalar projection of the vector u onto vector v.

We are given:

  • u = (5,1)(-5, 1)
  • v = (3,2)(-3, 2)

1. Scalar projection scalvu\text{scal}_{\mathbf{v}}\mathbf{u}

The scalar projection formula is: scalvu=uvv\text{scal}_{\mathbf{v}}\mathbf{u} = \frac{\mathbf{u} \cdot \mathbf{v}}{|\mathbf{v}|}

  • Dot product: uv=(5)(3)+(1)(2)=15+2=17\mathbf{u} \cdot \mathbf{v} = (-5)(-3) + (1)(2) = 15 + 2 = 17
  • Magnitude of v: v=(3)2+22=9+4=13|\mathbf{v}| = \sqrt{(-3)^2 + 2^2} = \sqrt{9 + 4} = \sqrt{13}

Thus, the scalar projection is: scalvu=1713\text{scal}_{\mathbf{v}}\mathbf{u} = \frac{17}{\sqrt{13}}

2. Vector projection projvu\text{proj}_{\mathbf{v}}\mathbf{u}

The formula for the vector projection is: projvu=uvvvv\text{proj}_{\mathbf{v}}\mathbf{u} = \frac{\mathbf{u} \cdot \mathbf{v}}{\mathbf{v} \cdot \mathbf{v}} \mathbf{v}

  • Dot product: vv=(3)2+22=9+4=13\mathbf{v} \cdot \mathbf{v} = (-3)^2 + 2^2 = 9 + 4 = 13
  • Projection factor: 1713\frac{17}{13}

Thus, the vector projection is: projvu=1713v=1713(3,2)=(5113,3413)\text{proj}_{\mathbf{v}}\mathbf{u} = \frac{17}{13} \mathbf{v} = \frac{17}{13}(-3, 2) = \left(\frac{-51}{13}, \frac{34}{13}\right)

Final answers:

  • projvu=(5113,3413)\text{proj}_{\mathbf{v}}\mathbf{u} = \left(\frac{-51}{13}, \frac{34}{13}\right)
  • scalvu=1713\text{scal}_{\mathbf{v}}\mathbf{u} = \frac{17}{\sqrt{13}}

Would you like more details on these calculations, or do you have any questions?

Here are 5 related questions:

  1. How is the dot product of two vectors calculated?
  2. What is the geometric meaning of vector projection?
  3. How does the magnitude of a vector affect its projection?
  4. Can the projection of a vector be zero? Under what conditions?
  5. How does the scalar projection differ from the vector projection?

Tip: Always make sure to simplify radical expressions when possible to keep answers in the simplest form.

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Math Problem Analysis

Mathematical Concepts

Vector Analysis
Dot Product
Vector Projection

Formulas

Dot Product: u . v = (u1 * v1) + (u2 * v2)
Magnitude of a Vector: |v| = sqrt(v1^2 + v2^2)
Scalar Projection: scal_v u = (u . v) / |v|
Vector Projection: proj_v u = ((u . v) / (v . v)) * v

Theorems

Vector Projection Properties

Suitable Grade Level

University Level