I have a quick question regarding this q:

Which of the following involve an iterative process?

a)

b)

c)

d)substituting a value for the variable in a quadratic equation

e)

I just need help with part d).. So I am confused with this one. My teacher at school said that this part d) WAS an iterative process. But, when I got home and did this question, the back of the book says that it is not an iterative process.

Can someone explain to me if this is or is not iteration? What would the difference between this example: subing in a value for the variable in a quadratic equation, and the recursion formula be?