Since it is within 0.001mm, then that means that if the diameter is 5+x,
5+x>4.999 (due to that 5-0.001=4.999) and 5+x<5.001 (since 5+0.001=5.001 and therefore has to be less than that), getting 4.999<5+x<5.001. Subtracting 5, we get -0.001<x<0.001. If we get the absolute value of everything, that means that |-0.001|>|x|<|0.001| (Note that since getting the absolute value of a negative number requires you to multiply it by -1, we switch the inequality around).Adding 5 back to it, we get 5+|x|>5+|0.001|
