Answer:
The value of c is 1/2
Explanation:
We have to find the value of c that completes the square

So, completing square is of form:

In the question given the value c can be found by breaking the middle term. we are given -x while the general formula is 2ab for middle term so, our c = 1/2 i.e 2(x)(1/2) we get x so, solving:

The value of c is 1/2