Integrated circuits

I am trying to find the final equations for outputs f1 and f2 from the truth table below.

inputs outputs
a b c d fi f2
0 0 0 0 0 1
0 0 0 1 0 1
0 0 1 0 0 0
0 0 1 1 1 0
0 1 0 0 0 1
0 1 0 1 0 1
0 1 1 0 0 1
0 1 1 1 1 1
1 0 0 0 0 0
1 0 0 1 1 1
1 0 1 0 0 0
1 0 1 1 1 1
1 1 0 0 0 0
1 1 0 1 1 1
1 1 1 0 0 0
1 1 1 1 1 0

For f1 I have d(/a.c +a)
for f2, i have tried but am not able to do it. If someone can take me through the steps in solving this, I would appreciate it.