PLEASE HELP I keep trying to figure it out

Need ! give step by step solutions on how to solve number one \frac{9-2\sqrt{3} }{12+\sqrt{3} } number two x+4=\sqrt{13x-20} number three (domain and range) f(x)=2\sqrt[3]{x} +1

What is the value of the expression 9+n/3-6 when n = 12? 1. 5. 7. 12.

Using inductive reasoning, what are the next two number in this set? 2,3/2,4/3,5/4,