The linear function y=mx+by=mx+b actually represents a graph of a straight line that has a point of intersection with the vertical Y Y axis.

m m represents the slope.
When m m is positive, the slope is positive: the line goes upwards.
When m m is negative, the slope is negative: the line goes downwards.
When m=0 m = 0 , the slope is zero: the line is parallel to the X X axis.

b b represents the point where the line intersects the Y Y axis.
If b=0 b=0 , then the line will pass through the origin of the coordinates, that is, the point (0,0) \left(0,0\right)

A - The Linear Function y=mx+b

Practice Linear Function y=mx+b

Examples with solutions for Linear Function y=mx+b

Exercise #1

Which best describes the function below?

y=23x y=2-3x

Video Solution

Step-by-Step Solution

Remember that the rate of change equals the slope.

In this function:

m=3 m=-3

Therefore, the function is decreasing.

Answer

The function is decreasing.

Exercise #2

Given the linear function:

y=x4 y=x-4

What is the rate of change of the function?

Video Solution

Step-by-Step Solution

Let's remember that the rate of change equals the slope.

In this case, the slope is:

m=1 m=1

Answer

m=1 m=1

Exercise #3

Calculate the slope of the line that passes through the points (4,1),(2,5) (4,1),(2,5) .

Video Solution

Step-by-Step Solution

Remember the formula for calculating a slope using points:

Now, replace the data in the formula with our own:

(51)(24)=42=2 \frac{(5-1)}{(2-4)}=\frac{4}{-2}=-2

Answer

-2

Exercise #4

What is the slope of a straight line that passes through the points (0,0),(8,2) (0,0),(-8,2) ?

Video Solution

Step-by-Step Solution

To solve the problem, remember the formula to find the slope using two points

 

Now, we replace the given points in the calculation:

 (02)(0(8)=28=14 \frac{(0-2)}{(0-(-8)}=\frac{-2}{8}=-\frac{1}{4}

Answer

14 -\frac{1}{4}

Exercise #5

Choose the correct answer for the function.

y=x+1 y=-x+1

Video Solution

Step-by-Step Solution

Let's start with option A

In a linear function, to check if the functions are parallel, you must verify if their slope is the same.

y = ax+b

The slope is a

In the original formula:

 y = -x+1

The slope is 1

In option A there is no a at all, which means it equals 1, which means the slope is not the same and the option is incorrect.

 

Option B:

To check if the function passes through the points, we will try to place them in the function:

-1 = -(-2)+1

-1 = 2+1

-1 = 3

The points do not match, and therefore the function does not pass through this point.

 

Option C:

We rearrange the function, in a way that is more convenient:

y = -1-x

y = -x-1

You can see that the slope in the function is the same as we found for the original function (-1), so this is the solution!

 

Option D:

When the slope is negative, the function is decreasing, as the slope is -1, the function is negative and this answer is incorrect.

Answer

The graph is parallel to the graph of function

y=1x y=-1-x

Exercise #6

For the function in front of you, the slope is?

XY

Video Solution

Answer

Negative slope

Exercise #7

For the function in front of you, the slope is?

XY

Video Solution

Answer

Negative slope

Exercise #8

For the function in front of you, the slope is?

XY

Video Solution

Answer

Positive slope

Exercise #9

For the function in front of you, the slope is?

XY

Video Solution

Answer

Positive slope

Exercise #10

For the function in front of you, the slope is?

XY

Video Solution

Answer

Positive slope

Exercise #11

For the function in front of you, the slope is?

XY

Video Solution

Answer

Positive slope

Exercise #12

For the function in front of you, the slope is?

XY

Video Solution

Answer

Negative slope

Exercise #13

For the function in front of you, the slope is?

XY

Video Solution

Answer

Negative slope

Exercise #14

For the function in front of you, the slope is?

XY

Video Solution

Answer

Negative slope

Exercise #15

For the function in front of you, the slope is?

XY

Video Solution

Answer

Negative slope

Topics learned in later sections

  1. Function
  2. Linear Function
  3. Slope in the Function y=mx
  4. Positive and Negativity of a Linear Function
  5. Finding a Linear Equation
  6. Graphs of Direct Proportionality Functions
  7. Representation of Phenomena Using Linear Functions