Adrian solved the equation x2+9=16 using the following steps. Review his work carefully, and then follow the instructions.

Line 1: x2+9=16
Line 2: x+3=±4
Line 3: x+3−3=±4−3
Line 4: x=1 and x=−7
Which statement identifies a mistake Adrian made, if any?

1) In Line 2, he should have subtracted 9 from both sides of the equation because it is not part of the expression that is squared.
2) He did not make a mistake. His answer is correct.
3) In Line 3, he should have added 3 to both sides of the equation to get ±4+3.
4) In Line 4, he subtracted incorrectly. The solutions should be x=±1 and x=±7.