Carlos,
The key to answering this question is to realize that the Pythagorean Theorem can help you. These two points can be considered to form the vertices of a hypotenuse of a right triangle, something like the one shown below (Wyzant made me delete the triangle.)
A(4, -3) B(6, -2)
The distance between these two given points is the hypotenuse of the triangle, h. The Pythagorean Theorem says that: h2 = a2 + b2
So, we need a and b so that we can calculate h.
To determine a, we subtract the two y-coordinates.
–2 – (–3) = –2 + 3 = 1 = a
To determine b, we subtract the two x-coordinates.
6 – 4 = 2 = b
Now, we fill in the values of a and b that we have calculated in the Pythagorean Theorem equation.
h2 = a2 + b2
h2 = 12 + 22
h2 = 1 + 4
h2 = 5
h = √5