ValueError: operands could not be broadcast together with shapes (5,) (30,)

I am trying to merge arrays like this:

If:

a = [1.2, 1, 3, 4]
b = [0.0 , 0.0]
c = [0.0 , 0.0]
a = a + b + c

Then the result should be:

[0.0 , 0.0 , 1.2 , 1 ,3 ,4 , 0.0 ,0.0]

what I do is that extract histogram of array and merge it with normal array.

x1, bins, patch = plt.hist(array1, bins = round(max(array1) - min(array1)))
x1 = b + x1 + c

but the form of x1 is 
x1 = [  2.   0.   0.   1.   0.   2.   5.   0.   1.   1.   0.   1.   5.]

and maybe that cause the error like this

ValueError: operands could not be broadcast together with shapes (5,) (30,)

please help me. I don’t know what to do