FIND VALUES OF FUNCTIONS FROM GRAPHS

About "Find values of functions from graphs"

Find values of functions from graphs :

Here we are going to learn how to find values of function from graph.

If a point (x, y) is on a function f,  then f(x) = y. In other words, y  is the output of f when the input is x.

Let us see an example problem to understand how to find the values of the function from the graphs.

Example 1 :

Use this graph of f to find f(5).

Solution :

By comparing the given question f(5) with f(x), we come to know that the value of x is 5, that is input. From this we have to find the value of y, that is output.

To know that let us draw a vertical line passing through the point 5 on x axis. 

Now check the line where it intersects the curve. From that particular point we have to draw a horizontal line which passes through y-axis.

Write the x and y coordinate values of that marked point. From the point (5, 2), we come to know that f(5) = 2.

Example 2 :

Use this graph of f to find f(4).

Solution :

By comparing the given question f(4) with f(x), we come to know that the value of x is 4, that is input. From this we have to find the value of y, that is output.

To know that let us draw a vertical line passing through the point 4 on x axis. 

Now check the line where it intersects the curve. From that particular point we have to draw a horizontal line which passes through y-axis.

Write the x and y coordinate values of that marked point. From the point (4, 5), we come to know that f(4) = 5.

Example 3 :

Use this graph of f to find f(2).

Solution :

By comparing the given question f(2) with f(x), we come to know that the value of x is 2, that is input. From this we have to find the value of y, that is output.

To know that let us draw a vertical line passing through the point 2 on x axis. 

Now check the line where it intersects the curve. From that particular point we have to draw a horizontal line which passes through y-axis.

Write the x and y coordinate values of that marked point. From the point (2, 7), we come to know that f(2) = 7.

Example 4 :

Use this graph of f to find f(4).

Solution :

By comparing the given question f(4) with f(x), we come to know that the value of x is 4, that is input. From this we have to find the value of y, that is output.

To know that let us draw a vertical line passing through the point 4 on x axis. 

Now check the line where it intersects the curve. From that particular point we have to draw a horizontal line which passes through y-axis.

Write the x and y coordinate values of that marked point. From the point (4, 4), we come to know that f(4) = 4.

After having gone through the stuff given above, we hope that the students would have understood "Find values of functions from graphs". 

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