Representation of Phenomena Using Linear Functions

🏆Practice representation of phenomena

A linear function describes the relationship between X X and Y Y .
Therefore, we can represent all sorts of different phenomena in life with the help of the linear function.
The representation of phenomena with the help of linear functions is expressed in mathematics in word problems, using graphs of the functions.
Thus, we can find the various relationships between the functions.

Representing phenomena using linear functions actually allows us to simplify many word questions using a simple linear graph. From the graph, we can very easily calculate the slope, which is actually the rate of change and even many other parameters.

A - Representation of Phenomena Using Linear Functions

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The graph below depicts the price of apples relative to the quantity.

How many kg of apples can you buy for $9?

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Example of representing phenomena using linear functions

At 10 10 in the morning, truck A A left the factory in Valencia for the factory in Madrid, a distance of 380 380 km.
At the same time, truck B B left the factory in Madrid for the factory in Valencia.

The two trucks were supposed to meet somewhere along the way.
The figure in front of you shows graphs that describe the position of the drivers at any time during the journey.

A1 - Distance (km) from Valencia and Time


What does each marked point on the graph mean?

Solution:
Let's first look at the points on the blue graph:
We can associate the blue graph with truck A A since we see it started from the point (0,0 0,0 ).
Truck A A departed from a point which is the distance from Valencia was 0 0 km, meaning it left from Valencia. Therefore, the point (0,0 0,0 ) is the starting point of truck A A . The second point on the blue graph: ( 12,380 12,380 ) represents the arrival point of truck A A in Madrid.
After 12 hours and after 380 380 km.

Now let's look at the points on the purple graph:
(3.8,0 3.8,0 ) this point represents truck B B and shows us that after 3.8 3.8 hours, the truck arrived in Valencia: its distance from Valencia was 0 0 km.
(0,380 ): represents truck B B and shows us its starting point where it had not yet begun to travel and its distance to Valencia was 380 380 km.


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When and at what distance did the two trucks meet?

To answer this question, we will have to find the equations of the two lines and solve a system of equations with two variables.

We will find the equation of truck A A with the help of the 2 2 given points.
We will do the same for truck B B .
The two equations we obtain will form a system of equations with two variables. We will solve the system and obtain the meeting point between the two trucks.

In terms of time, we will obtain the value X X and in terms of distance from Valencia, we will obtain the value Y Y .


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In the blog of Tutorela you will find a variety of articles about mathematics.


Examples and exercises with solutions for representing phenomena using linear functions

Exercise #1

The graph below depicts the price of apples relative to the quantity.

How many kg of apples can you buy for $9?

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Video Solution

Step-by-Step Solution

Let's look at the Y-axis which shows us the price data. Locate 9 dollars - and mark a point.

From this point, we'll draw a vertical line until we meet the straight line.

Now let's look at the X-axis which shows us the quantity in kg.

We'll draw a line from the point where we reached the Y-axis to the straight line, towards the X-axis and determine the weight: 8 kg.

Answer

8

Exercise #2

The graph below depicts the price of apples relative to the quantity.

What is the price of 7 kg of apples?

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Video Solution

Step-by-Step Solution

Let's look at the X-axis which shows us the weight. Locate 7 kg - and mark a point.

From this point, we'll draw a vertical line until we meet the straight line.

Now let's look at the Y-axis which shows us the price.

We'll draw a line from the point where we reached the X-axis to the straight line, towards the Y-axis and determine the price: 8 dollars.

Answer

8

Exercise #3

The graph below depicts the price of tomatoes as a function of quantity, with each line representing the prices at different shops.

Where is it cheaper to buy 7 kg of tomatoes?

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Video Solution

Step-by-Step Solution

Let's look at the red line:

The X-axis shows us the quantity, we'll locate 7 kg and from it draw a vertical line to the line - mark a point.

From this point we'll draw a horizontal line to the Y-axis which shows the price and we'll see that 7 kg costs 8 NIS.

Let's look at the blue line:

The X-axis shows us the quantity, we'll locate 7 kg and from it draw a vertical line to the line - mark a point.

From this point we'll draw a horizontal line to the Y-axis which shows the price and we'll see that 7 kg costs 10 NIS.

Therefore it's better to buy at the red store, it's cheaper.

Answer

In the red shop

Exercise #4

There are two water containers. The first container is empty, whilst the second contains 48 liters of water.

After how many minutes will the second container be completely full?

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Step-by-Step Solution

Let's look at the blue line that represents the second container.

Notice that it will be full at the point where it starts to become a continuous line.

Let's draw a vertical line from this point to the X-axis which marks the minutes.

We can see that the line reaches 22, meaning the container will be full in 22 minutes.

Answer

22 minutes

Exercise #5

A car leaves Madrid for Barcelona. During the journey, the driver has a break.

For how many hours did the driver rest?

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Video Solution

Answer

6

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