In[]:=
Exp1=Times[128,Power[a,3],Pi,Power[Plus[Power[Plus[m,Times[-1,M]],2],Times[-1,s],Times[-1,t]],Rational[-1,2]],Plus[Power[m,2],Power[M,2],Times[-1,s],Times[-1,t]],Power[Plus[Power[Plus[m,M],2],Times[-1,s],Times[-1,t]],Rational[-1,2]],Power[t,-2],Plus[Times[2,Power[Plus[Power[m,2],Power[M,2],Times[-1,s]],2]],Times[2,s,t],Power[t,2]],Plus[Log[Times[2,m,M]],Times[-1,Log[Plus[Times[-1,Power[m,2]],Times[-1,Power[M,2]],s,Times[Power[Plus[Power[Plus[m,Times[-1,M]],2],Times[-1,s],Times[-1,t]],Rational[1,2]],Power[Plus[Power[Plus[m,M],2],Times[-1,s],Times[-1,t]],Rational[1,2]]],t]]]]];
In[]:=
Exp2=Times[-128,Power[a,3],Pi,Plus[Power[m,2],Power[M,2],Times[-1,s],Times[-1,t]],Power[t,-2],Plus[Times[2,Power[Plus[Power[m,2],Power[M,2],Times[-1,s]],2]],Times[2,s,t],Power[t,2]],Power[Plus[Power[m,4],Power[Plus[Times[-1,Power[M,2]],s,t],2],Times[-2,Power[m,2],Plus[Power[M,2],s,t]]],Rational[-1,2]],Plus[Log[Times[2,m,M]],Times[-1,Log[Plus[Times[-1,Power[m,2]],Times[-1,Power[M,2]],s,t,Power[Plus[Power[m,4],Power[Plus[Times[-1,Power[M,2]],s,t],2],Times[-2,Power[m,2],Plus[Power[M,2],s,t]]],Rational[1,2]]]]]]];
In[]:=
Exp1+Exp2//FullSimplify
Out[]=
1
2
t
128
3
a
π(
2
m
+
2
M
-s-t)(2
2
(
2
m
+
2
M
-s)
+2st+
2
t
)
Log[2mM]-Log-
2
m
-
2
M
+s+
2
(m-M)
-s-t
2
(m+M)
-s-t
+t
2
(m-M)
-s-t
2
(m+M)
-s-t
+
-Log[2mM]+Log-
2
m
-
2
M
+s+t+
4
m
+
2
(-
2
M
+s+t)
-2
2
m
(
2
M
+s+t)

4
m
+
2
(-
2
M
+s+t)
-2
2
m
(
2
M
+s+t)
In[]:=
FullSimplify[Exp1+Exp2,Assumptions{t!=0,m=Range[10],s=Range[10],t=Range[10],M=Range[10],a=Range[10]}]
Out[]=
{0,0,0,0,0,0,0,0,0,0}
In[]:=
FullSimplify[Exp1+Exp2,Assumptions{t=0,m=Range[10],s=Range[10],t=Range[10],M=Range[10],a=Range[10]}]
Out[]=
{0.+0.,0.+0.,-1.86265×
-9
10
+0.,3.72529×
-9
10
+0.,-7.45058×
-9
10
+1.65436×
-24
10
,-1.49012×
-8
10
+0.,0.+0.,0.+0.,2.98023×
-8
10
+0.,-5.96046×
-8
10
+2.64698×
-23
10
}