We need to use the distance formula here
[tex] d = \sqrt{(x_2 - x_1)^2+(y_2-y_1)^2} [/tex]
Now, substitute in the points (1, 2) and (-4, 2)
[tex] d = \sqrt{(-4-1)^2 + (2-2)^2} [/tex]
Simplify
[tex]d = \sqrt{(-5)^2 + 0^2} [/tex]
[tex]d = \sqrt{25} [/tex]
d = 5
