So let's evaluate a point that is to the left of (which is the left most endpoint). Let's evaluate the value
Start with the given inequality
Plug in
Evaluate and simplify
Since is false, this means that the interval does not work. So that means that this interval is not in the solution set and can be ignored.
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Now let's test a point that is in between the critical values and
Start with the given inequality
Plug in
Evaluate and simplify
So the graph now looks like
Since is true, this means that one part of the solution in interval notation is []
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So let's evaluate a point that is to the right of (which is the right most endpoint). Let's evaluate the value
Start with the given inequality
Plug in
Evaluate and simplify
Since is false, this means that the interval does not work. So that means that this interval is not in the solution set and can be ignored.
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