I need help, This is due tmmow and I don't understand any of it, I just need answers

How many different three-digit numbers can be formed using the digits 1 comma 2 comma 9 comma 6 comma 4 comma 3 comma and 8 without repetition? for example, 664 is not allowed.

Select the correct answer what is the 10th term of the geometric sequence 3,6, 12, 24,48 a. 512 b. 3,072 c. 768 d. 1,536

Define the type of sequence below. -2,0,2,4,6 a. both arithmetic and geometric b. arithmetic c. neither arithmetic nor geometric d. geometric