Question

Please solve for the interval notation corresponding to the set notation
{x | x < –7}

Answer 1

See answer to Rachale's question.
http://www.jiskha.com/display.cgi?id=1243987256

Answer 2

Thank you, but why is it
(-infinity -7)?

is it translated to
negative infinity - 7?

Answer 3

> [-5,8) is the same as {x|-5=<x<8}
meaning that the square bracket [ includes the lower limit, while the ] includes the upper limit. The limits are separated by a comma.

You are right in actual practice, it is normal to exclude infinity or negative infinity. In my books, -infinity is a short form for negative infinity.

So the correct answer would be:
<b>(negative infinity, -7)</b>

Answer 4

Thank you for the explanation!