Here are some thoughts on Question 2: If a=2b and b =4c, then ³√[a²/16bc].
*It requires to determine the value of ³√[a²/16bc]. Since the exact values of a, b, c are not provided, we need to know the relationships among a, b, c and make appropriate substitutions to factorize ³√[a²/16bc].
*The provided constraints, i.e., a=2b and b=4c, are just what we want to know---the relationships among a, b, c.
*From a=2b and b=4c we observe that both a and c relate to b. So we could substitute a and c in ³√[a²/16bc] with b. More specifically, we have a=2b and c=b/4.
*Now transform ³√[a²/16bc] to ³√[(2b)²/16b(b/4)] and I'm sure you could proceed with the rest