\begin{tabular}{|c|c|c|c|}
\hline
& 8 & & 1 \\
\hline
& 11 & & 14 \\
\hline
3 & 10 & & \\
\hline
56 & 5 & 9 & 4 \\
\hline
\end{tabular}

The sum is 34.



Answer :

Sure, let's determine the missing values in the grid ensuring that every row, column, and diagonal sums to 34.

### Grid Representation

Here is the grid with spaces where values are missing:

```
| | 8 | | 1 |
| | 11 | | 14 |
| 3 | 10 | | |
| 56 | 5 | 9 | 4 |
```

### Step-by-Step Solution

#### Checking the Sums

1. Sum of the fourth row:
The fourth row has the values `56, 5, 9, 4`.
Let's sum them up:
```
56 + 5 + 9 + 4 = 74
```
So, the sum of the fourth row is 74.

2. Target Sum: It is given that the target sum for each row, column, and diagonal is 34.

3. Inconsistent row sum:
Notice that the sum of the last row provided is 74, which is already greater than the target sum of 34. Thus, it's impossible for the fourth row to conform to the sum constraint of 34 when the fixed elements in this row sum to 74.

4. Identifying the discrepancy:
The provided target sum for each row, column, and diagonal is indeed 34, but having a last row that sums to 74 implies a discrepancy or misalignment in the problem's constraints or provided values.

Given these findings, there is an inconsistency in the problem setup with the actual values summing to different amounts than what is specified as the target. Specifically, the fourth row with values 56, 5, 9, and 4 summing to 74 cannot be reconciled with a target sum of 34 for every row, column, and diagonal.

### Conclusion

Due to the inconsistency observed with the fourth row not aligning with the target sum constraint provided in the question, the grid cannot be completed in a way that every row, column, and diagonal sums to 34. However, if this discrepancy is intentionally part of a more complex or different type of problem setup, further clarification would be necessary to properly align the problem's given constraints with the expected solutions.