Take a look at the function f(x) = √(x-1). The input to the square root function MUST be ≥ 0. Write and solve the inequality x-1 ≥ 0:
Adding 1 to both sides, we get x ≥ 1, or [1,infinity). This is the domain, the set of numbers for which f(x) is defined.
The smallest value that f(x) = √(x-1) can take on is 0 (at x=1). Thus, the range is y≥0. or [0,infinity). The range is the set of all possible output values of the function with which we are concerned.
First get the formula for your pattern in the form of TN. Where d represents your difference and a represents your first term. Then equate the -401 to your formula and solve for n
