Algebra
posted by Rachale on .
Write the interval notation corresponding to the set notation
{x  x < –7}.

Since
[5,8) is the same as {x5=<x<8}
we have
{xx<7}
in interval notation
[infinity, 7) 
Thank you, but why is it
(infinity 7)?
is it translated to
negative infinity  7? 
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:
(negative infinity, 7)