Using the standard format of a perfect-square quadratic sum, it is found that the value that completes the expression is 169.
It is represented by:
(a + b)² = a² + 2ab + b².
In this problem, we have that the expression is:
a² + 2ab + b² = h² + 26 + b².
Hence a = 1, 2ab = 26 -> b = 13, thus the value that completes the expression is:
b² = 13² = 169.
More can be learned about perfect-squares at https://brainly.com/question/13136492