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Cartesian graph construction of a function


To graph a function f, simply assign domain values ​​to variable x and, using the mathematical sentence that defines the function, calculate the corresponding values ​​of variable y.

Let's build the graph of the function defined by y = x / 2. We chose some values ​​for the domain, such as D = {2,4,6,8}. Now we calculate the respective values ​​of y. Thus we have:

x = 2 y = 2/2 = 1
x = 4 y = 4/2 = 2
x = 6 y = 6/2 = 3
x = 8 y = 8/2 = 4

So we set up the following table:

We identified the points found in the Cartesian plane:

The graph of the function will be a line that will pass through the four points found. Just draw the line, and the graph will be built.

Note: To draw the graph of a line only two points are required. In the example above we chose 4 points, but it would be enough to choose two elements of the domain, find their images, and then draw the line that goes through these 2 points.

Next: Roots of a Function