Please answer correctly and no links​

4. find the geometric mean of 4 and 12. 24 8

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

Which of the following is the equation that says that the product of a number and ten is equal to 20 percent of that number ? a) 10n= 2.0n b) 10+n=.20n c) n+ .20n=10 d) 10n=0.20n