Question

The problem is in the picture :)

Answer 1

Last option: 4

Explanation:

The quadratic equation simplified:
`x^2-4x=-(7)/(2)` has the form:

`ax^2+bx=c`

In this case, you can identify that "a", "b" and "c" are:

`a=1\\b=-4\\c=-(7)/(2)`

To solve this quadratic equation by completing the square, Carlos should add
`((b)/(2))^2` to both sides of the equation. This is:

`((-4)/(2))^2=(-2)^2=4`

Then:

`x^2-4x+4=-(7)/(2)+4`

Therefore you can observe that the number he should add to both sides of the equation is: 4