Dynamically append each values into 2D slice

I wish to have a datastructure(array or slice) to look like this :

[[a b c d e][f g h i j] [k l m n o] 
 [u v w x y]] 

such that a is the distance between node from "A" to "A" . (which shall be 0)
b is the distance between node from "A" to "B" .
c is the distance between node from "A" to "C" .

f is the distance between node from "B" to "A" .
g is the distance between node from "B" to "B" . (which shall be 0)
h is the distance between node from "B" to "C" .

Now I have created a slice like :
var shortestPathSLice = make([][]int, 5) to store this 2D data.

In my for loop within a function, I am trying to fill this slice dynamically as follows :

shortestPathSLice = append(shortestPathSLice[0][index], lowEstimate[0])

where lowestimate[0] is value of the smallest distances between two nodes.

However, I get an error with this : first argument to append must be slice; have int

Can anyone tell me how can I dynamically append values in EACH ELEMENT in my slice ?

**CODE **

    var shortestPathSLice = make([][]int, 5)
    for index := 0; index < len(t.Location_ids); index++ {
    lowEstimate := make([]int, len(priceestimatestruct.Prices))
    	for i := 0; i < len(priceestimatestruct.Prices); i++ {
    		lowEstimate[i] = priceestimatestruct.Prices[i].LowEstimate
    	}
    
    	sort.Ints(lowEstimate)
    	fmt.Println("LowEstimate array : ", lowEstimate)
    	shortestPathSLice[0] = make([]int, len(lowEstimate))
    	shortestPathSLice[0][index] = lowEstimate[0]
}

> The Go Programming Language Specification
>
> Appending to and copying slices
>
> The built-in functions append and copy assist in common slice
> operations. For both functions, the result is independent of whether
> the memory referenced by the arguments overlaps.
>
> The variadic function append appends zero or more values x to s of
> type S, which must be a slice type, and returns the resulting slice,
> also of type S. The values x are passed to a parameter of type ...T
> where T is the element type of S and the respective parameter passing
> rules apply. As a special case, append also accepts a first argument
> assignable to type []byte with a second argument of string type
> followed by .... This form appends the bytes of the string.
>
> append(s S, x ...T) S // T is the element type of S
>
> If the capacity of s is not large enough to fit the additional values,
> append allocates a new, sufficiently large underlying array that fits
> both the existing slice elements and the additional values. Otherwise,
> append re-uses the underlying array.

For example, using append and using an index,

package main
import "fmt"
func main() {
	{ // using append
		dim := 5
		matrix := make([][]int, dim) // dim*dim matrix
		for i := 0; i < dim; i++ {
			matrix[i] = make([]int, 0, dim)
			vector := make([]int, dim)
			for j := 0; j < dim; j++ {
				vector[j] = i*dim + j
				matrix[i] = append(matrix[i], vector[j])
			}
		}
		fmt.Println(matrix)
	}
	{ // using index
		dim := 5
		matrix := make([][]int, dim) // dim*dim matrix
		for i := range matrix {
			matrix[i] = make([]int, dim)
			vector := make([]int, dim)
			for j := range matrix[i] {
				vector[j] = i*dim + j
				matrix[i][j] = vector[j]
			}
		}
		fmt.Println(matrix)
	}
}

Output:

[[0 1 2 3 4] [5 6 7 8 9] [10 11 12 13 14] [15 16 17 18 19] [20 21 22 23 24]]
[[0 1 2 3 4] [5 6 7 8 9] [10 11 12 13 14] [15 16 17 18 19] [20 21 22 23 24]]