Answer:
1st option [1, infinity)
Step-by-step explanation:
the red interval starts left (on the low side) with 1 and continues to the right (the high side) without any end.
the 1 has a full dot, that means the number 1 itself is included in the interval.
but the left has no defined end. infinity is not a number and cannot be included as interval end.
so, the first answer option is correct.
the bracket at 1 indicates "included", white the parenthesis at "infinity" means "excluded".
no infinity (negative or positive) can ever be an included interval end.
and so, that is why you write this in the given way.
if the dot at 1 would be hollow, then that would mean that the value 1 itself would be excluded, and the second answer option would be right.
but it is not, so, the first option stays right.
the last 2 options are just nonsense. our red line/interval has nothing to do with the left end, the negative infinity.
