[[x]] means that the integer should be rounded down to the greatest integer that is of the same value as x or is lower than x.
I'm sorry that I'm not in calculus, but hopefully I can help.
Personally, I would choose: D.) x; in the second equation ;
because it has easier numbers to figure out, you'll get it eventually...
Answer:
1021
Step-by-step explanation:
1+1=2 and it needs to add up to 4 so you add in another 2 in the only place left for it to go which is in the tens place because the first and last number have to be the same and 0 has to go in the hundreds place.