Substitute each x-value into y = 2x − 1. The pairs where the computed y matches the given y are correct. A function gives an output for each input. To evaluate f(x), replace every x in the rule with the given number before simplifying. Be especially careful with negative inputs, because multiplying two negative signs can make a positive result. The correct choices are (1, 1), (−1, −3), (3, 5), (2, 3), because each of these satisfies the required condition.