Answer:
(-inf, 1]
Explanation:
Personal comment
Sorry this took so long
In short, you had it flipped, always put your smallest value first and your largest value second.
Reason:
Interval notation is
[(minima, maxima)]
Which is basically saying the minimum and the maximum, and as such you always end up having the smallest value first.
Putting the reasoning together;
A negative is always less than a positive in practice, therefore, your negative infinity should go first.
Hope this helps :)