Which expressions are equivalent? Choose all that apply 3^9, 3^4, -9^2, 9^9, 81^1

What is the equation of the graph below? y=sec(x)-4

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.

Find the domain of the following expression: 1/(√x)-2