Can someone explain these math questions to me

What is the square root of 45? (step by step working plz)

Iwill give brainliest only if your correct the words subsequent and submerge both contain the prefix sub. based on this information, what does the prefix sub most likely mean? a) under or secondary b) true or verifiable c) tricky or difficult d) around or centered on

Is it true or false i’m trying to pass this test so i can leave school