-1 is less than 0, so you use the first equation:
3(-1) +2 = -3+2 = -1
f(-1) = -1
For 0 use the 2nd equation:
3(0) + 4 = 0+4 = 4
f(0) = 4
For 2 use the 2nd equation:
3(2) + 4 = 6+4 = 10
f(2) = 10
Here is your solution,
(-5)^2 - √25 - 4 x (-14)/2
25 - √ 25 + 56/2
25 - √81/2
(25 - 9)/2 = 16/2 = 8
or
25 + √25 +56/2
25 + √81/2
(25 + 9)/2 = 34/2 = 17
So m = 8,17