Answer:
![c=(49)/(4)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/ncvc5kgpi246fbjtcyyefutltynouvmlvz.png)
Explanation:
You can find the value of "c" that will make it a perfect square trinomial by Completing the square.
Given the following expression provided in the exercise:
![x^2 - 7x + c](https://img.qammunity.org/2020/formulas/mathematics/middle-school/v3uggytrv1bu46h659kskmu23oejypzxco.png)
You can notice that it is written in this form:
![ax^2-bx+c](https://img.qammunity.org/2020/formulas/mathematics/middle-school/basa6v917emtg5k45w7akbh9vp97x8cy4i.png)
Then, you can identify that the coefficient "b" is:
![b=-7](https://img.qammunity.org/2020/formulas/mathematics/middle-school/gl2tkuvobpdylwuh92nz39bo9uhk76ecv1.png)
Since to complete the square you must add and subtract the half of square of coefficient "b", you can conclude that:
![c=((b)/(2))^2](https://img.qammunity.org/2020/formulas/mathematics/middle-school/tfqcxkm5gfteqccw3t9qmf2cn8bmlytqbt.png)
Therefore, substituting "b" into
, you get:
![c=((-7)/(2))^2\\\\c=(49)/(4)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/etaplby6n8m3e4r8g7ihg0c5v4em0gxzb4.png)