27
3x6
25
9, 18, 27, 36, 45, 54, 63, 72, 81, 90, 99 . . .
18
The numbers that add to get 6 and multiply to get 81 are 3 and 3.
Anything that isn't 9, 18, 27, 36, 45, 54, 63, 72, 81, 90, 99 and so on.
-27
Yes
9, 18 and 36
-3 and -6
The numbers are: 9 + square root of 129 and 9 - square root of 129
29
-52
-154
-25
the answer is 18
The factor pairs of 36 are (36, 1) (18, 2) (12, 3) (9, 4) (6, 6) None of them add up to 9. If that was -36, you could use 12 and -3
-25