Matrices and Vectors

Help Questions

Pre-Calculus › Matrices and Vectors

Questions 1 - 10
1

Find the dot product of the two vectors

and

.

Explanation

To find the dot product of two vectors,

find the product of the x-components,

find the product of the y-components,

and then find the sum.

2

Add:

Explanation

In order to add matrices, they have to be of the same dimension. In this case, they are both 2x2.

The formula to add matrices is as follows:

Plugging in our values to solve we get:

3

Find if and .

Explanation

To find the direction vector going from to , subtract the x and y-coordinates of from .

4

Write this vector in component form:

Vector 1

Explanation

To figure out the horizontal component, set up an equation involving cosine, since that side of the implied triangle is adjacent to the 48-degree angle:

To solve for x, first find the cosine of 48, then multiply by 11:

To figure out the vertical component, set up an equation involving sine, since that side of the implied triangle is opposite the 48-degree angle:

to solve for y, just like x, first find the sine of 48, then multiply by 11:

Putting this in component form results in the vector

5

Find the component form of the vector with

initial point

and

terminal point .

Explanation

To find the vector in component form given the initial and terminal points, simply subtract the initial point from the terminal point.

6

Find , then find its magnitude. and are both vectors.

Explanation

In vector addition, you simply add each component of the vectors to each other.

x component: .

y component: .

z component: .

The new vector is

.

To find the magnitude we use the formula,

Thus its magnitude is 5.

7

Find the dot product of the two vectors

and

.

Explanation

To find the dot product of two vectors,

find the product of the x-components,

find the product of the y-components,

and then find the sum.

8

Write the parametric equation for the line y = -3x +1.5

x = -3t +1.5

y = -3t +1.5

x = t

y = 1.5t - 3

x = t

y = -3t +1.5

x = -3t +1.5

y = t

Explanation

In the equation y = -3x +1.5, x is the independent variable and y is the dependent variable. In a parametric equation, t is the independent variable, and x and y are both dependent variables.

Start by setting the independent variables x and t equal to one another, and then you can write two parametric equations in terms of t:

x = t

y = -3t +1.5

9

Write an equation in slope-intercept form of the line with the given parametric equations:

Explanation

Start by solving each parametric equation for t:

Next, write an equation involving the expressions for t; since both are equal to t, we can set them equal to one another:

Multiply both sides by the LCD, 6:

Get y by itself to represent this as an equation in slope-intercept (y = mx + b) form:

10

Find the parametric equations for a line parallel to and passing through the point (0, 5).

x = 5t

y = 3 + 2t

x = 3 + 2t

y = 5t

x = 3

y = 2 + 5t

x = 3t

y = 5 + 2t

Explanation

A line through a point (x1,y1) that is parallel to the vector = (a1, a2) has the following parametric equations, where t is any real number.

Using the given vector and point, we get the following:

x = 3t

y = 5 + 2t

Each value of t creates a distinct (x, y) ordered pair. You can think of these points as representing positions of an object, and of t as representing time in seconds. Evaluating the parametric equations for a value of t gives us the coordinates of the position of the object after t seconds have passed.

Page 1 of 56