Not really a question, basic physics instructions (book error?)

[Raizy]

In this pic: http://img268.imageshack.us/i/imgp2719d.jpg/

I couldn't follow what's in the red box. I just hope anyone on here could look through it and tell me if there is some error in there. If not, then I feel stupid.

 

[songoku]

There is no mistake in that picture

$$a = \frac{\Delta v}{\Delta t}$$

 

[Raizy]

Why is it squaring delta t all of a sudden?

 

[cepheid]

Why is it squaring delta t all of a sudden?

You can see from the very first line in that rectangular box that we have $\Delta t (\Delta t)$.

 

[Raizy]

Ok, got it.