Examples with solutions for Linear Function y=mx+b: Calculate the slope from a table

Exercise #1

Below is a table containing values for x and y. This tables represents a linear function.

Choose the equation that corresponds to the function.

012x567y

Video Solution

Step-by-Step Solution

To solve this problem, we'll proceed with the following steps:

  • Step 1: Find the slope mm.
  • Step 2: Use the slope and a point to find the yy-intercept bb.
  • Step 3: Write the linear equation.

Let's work through each step:

Step 1: Calculate the slope mm.
Using the points (0,5)(0, 5) and (1,6)(1, 6), the slope mm is calculated as follows:

m=6510=11=1 m = \frac{6 - 5}{1 - 0} = \frac{1}{1} = 1

Step 2: Use the slope (m=1m = 1) to find the yy-intercept bb.
We know from the point (0,5)(0, 5) that when x=0x = 0, y=5y = 5, which directly gives us the yy-intercept:

b=5 b = 5

Step 3: Form the equation of the line using y=mx+by = mx + b.
Substitute the found values into the equation:

y=1x+5 y = 1 \cdot x + 5

Simplifying gives:

y=x+5 y = x + 5

Thus, the equation corresponding to the function is y=x+5 y = x + 5 .

Answer

y=x+5 y=x+5

Exercise #2

Below is a table containing values for x and y. This tables represents a linear function.

Choose the equation that corresponds to the function.

-2-11x42-2y

Video Solution

Step-by-Step Solution

To find the equation of the linear function corresponding to the given table, follow these steps:

  • Step 1: Identify Points
    We have three points from the table: (2,4)(-2, 4), (1,2)(-1, 2), and (1,2)(1, -2).
  • Step 2: Calculate the Slope
    The slope mm can be calculated using any two points. Choosing (2,4)(-2, 4) and (1,2)(-1, 2):
    m=y2y1x2x1=241(2)=21=2 m = \frac{y_2 - y_1}{x_2 - x_1} = \frac{2 - 4}{-1 - (-2)} = \frac{-2}{1} = -2 .
  • Step 3: Verify Linear Relationship
    Using (x,y)(x, y) pairs, check another pair such as (1,2)(-1, 2) and (1,2)(1, -2):
    m=221(1)=42=2 m = \frac{-2 - 2}{1 - (-1)} = \frac{-4}{2} = -2 .
  • Step 4: Select the Correct Equation
    The slope is 2-2, and since a linear function typically can be formatted as y=mx+by = mx + b, we can see if b=0b = 0 by trying one of the equations y=2xy = -2x given in the choices. Let’s check:
    For x=2x = -2: y=2(2)=4y = -2(-2) = 4. Matches.
    For x=1x = -1: y=2(1)=2y = -2(-1) = 2. Matches.
    For x=1x = 1: y=2(1)=2y = -2(1) = -2. Matches.
  • Therefore, the equation that corresponds to the function is y=2x y = -2x .

Answer

y=2x y=-2x

Exercise #3

Below is a table containing values for x and y. This tables represents a linear function.

Choose the equation that corresponds to the function.

10-1x1074y213

Video Solution

Step-by-Step Solution

To determine the equation of the linear function from the given table, we'll follow these steps:

  • Step 1: Calculate the Slope (m m )
  • Step 2: Find the Y-intercept (b b )
  • Step 3: Formulate the Linear Equation

Let's delve into each step:

Step 1: Calculate the Slope (m m )
Using two points from the table, (2,13)(2, 13) and (1,10)(1, 10), we calculate the slope m m using the formula:

m=y2y1x2x1=101312=31=3 m = \frac{y_2 - y_1}{x_2 - x_1} = \frac{10 - 13}{1 - 2} = \frac{-3}{-1} = 3

Thus, the slope m m is 3.

Step 2: Find the Y-intercept (b b )
The y-intercept b b is easily found because it is where x=0 x = 0 . From the table, when x=0 x = 0 , y=7 y = 7 , therefore b=7 b = 7 .

Step 3: Formulate the Linear Equation
Substitute the values of m m and b b into the linear equation format:

y=3x+7 y = 3x + 7

Hence, the equation that represents the linear function is y=3x+7 y = 3x + 7 .

Checking against the provided choices, the equation corresponds to choice 2.

Answer

y=3x+7 y=3x+7

Exercise #4

Given the two tables of values x and and.

These tables represent a linear function. Fit an equation of a linear function to each one.

10-1x6810y24

Video Solution

Step-by-Step Solution

To solve for the linear function, we need to follow these structured steps:

Step 1: Calculate the slope (m m ).

Use the points (1,10)(-1, 10) and (0,8) (0, 8) . The slope m=8100(1)=21=2 m = \frac{8 - 10}{0 - (-1)} = \frac{-2}{1} = -2 .

Step 2: Determine the y-intercept (b b ).

Use the point-slope form with the point (0,8) (0, 8) (since x=0 x = 0 is the y-intercept directly). Thus, b=8 b = 8 .

Step 3: Write the equation of the line.

The equation fitting the table values is y=2x+8 y = -2x + 8 .

Therefore, the equation of the linear function is y=2x+8 y = -2x + 8 .

Answer

y=2x+8 y=-2x+8