I am trying to find the final equations for f1 and f2 from 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 fi my answer is d(/a.c+a), am unable to solve f2. if someone can take me through the steps in solving this I would appreciate it.

 

To solve that you can use a Karnaugh Map. For details see: Chapter 8: KARNAUGH MAPPING

 

You might find the following extra relations helpful in making algebraic reductions.
using A' for negation or complement.

A+AB=A

A(A+B)=A

A(A'+B)=AB

A+A'B=(A+A')(A+B)=A+B

A+BC=(A+B)(A+C)

A+A+A+...=nA=A

A.A.A.....=A^n=A