If a = (7, 9) and b = (3, 12), what is the length of ab

The Pythagorean theorem is used to find the distance between two points. If that distance is "c", it satisfies the relation

... a² + b² = c²

where "a" and "b" are the horizontal and vertical differences between the point coordinates. Here,

... a = 7 - 3 = 4 . . . . horizontal difference

... b = 12 - 9 = 3 . . . . vertical difference

Then we have

... 4² + 3² = c² = 25

... c = √25 = 5

The length of AB is 5 units.

4x and 6y

im not sure though