I am sorry because probably is a stupid question but how can I multiply a symbol letter for a vector list
c = a.{1, 1} + b.{3, 4}
I would like expand this as {a,a}+{3b,4b} and finally in {a+3b,a+4b}
Thanks in advance.
In Mathematica the dot is used for inner product between two vectors. For your purpose use the asterisk * (or nothing at all, in this case):
a*{1, 1} + b*{3, 4} a{1, 1} + b{3, 4}
In[2]:= Clear[a, b] a {1, 1} + b {3, 4} Out[3]= {a + 3 b, a + 4 b} In[4]:= Times[a, {1, 1}] + Times[b, {3, 4}] Out[4]= {a + 3 b, a + 4 b}