How do you graph f(x)=|x+4|3?

1 Answer
Aug 10, 2015

graph{|x+4|-3 [-10, 10, -5, 5]}

Explanation:

Start from the definition of an absolute value function.
It looks like this:
for any non-negative real number its absolute value is itself;
for any negative real number its absolute value is its opposite.
So, for example, |3.14|=3.14, |0|=0, |2.71|=2.71 etc.

Let's draw a simple graph of a function y=|x|.

For non-negative x it coincides with a function y=x, that is, it's a straight line at angle 45o to X-axis, measured from the positive direction of the X-axis counterclockwise.

For negative x it coincides with a function y=x, that is, it's a straight line at angle 135o to X-axis, measured from the positive direction of the X-axis counterclockwise or, which is the same, at angle 45o to X-axis, measured from the negative direction of the X-axis clockwise.

Combining both parts of a graph, we obtain the following graph for function y=|x|:

graph{|x| [-10, 10, -5, 5]}

Next step is to transform this graph to y=|x+4|.
As can be easily observed, the original function y=|x| takes the same values (y values) as the new function y=|x+4| for arguments x smaller by 4. Therefore, the graph of y=|x+4| is shifted by 4 to the left from the original y=|x| and looks like this:

graph{|x+4| [-10, 10, -5, 5]}

The last step is to transform graph y=|x+4| to y=|x+4|3.
As can be easily observed, the new function y=|x+4|3 takes the values (y values) smaller by 3 than the old function y=|x+4| for the same arguments x. Therefore, the graph of y=|x+4|3 is shifted by 3 down from the graph of function y=|x+4| and looks like this:

graph{|x+4|-3 [-10, 10, -5, 5]}

We recommend to watch the series of lectures about graphs on Unizor by following the menu Algebra - Graphs