How to get this equation ??

[loveinharovrd]

**broken link removed**

How to get the second equation?

Thanks a million ！！

 

[iyami]

| sin(x) - sin | <= | x - y |

because

| sin(x) - sin | = | (x - y) * sin'(z)| for some z in the interval [x,y] or [y, x]

and

sin' = cos and |cos(z)| <= 1 for all z.

Since this is true for all x and y it is also true for sqr(x) and sqr(x+1)