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Iteration question

In this video: https://www.youtube.com/watch?time_continue=315&v=gfKu1ILeVdg , Jack Brown says you get a staircase if the gradient of the root is positive and a cobweb if it's negative, but then towards the end says it's possible to get both so I'm a bit confused, because in the example he gives at the end to show this has the gradient of the root being negative.
Reply 1
Original post by dont know it
In this video: https://www.youtube.com/watch?time_continue=315&v=gfKu1ILeVdg , Jack Brown says you get a staircase if the gradient of the root is positive and a cobweb if it's negative, but then towards the end says it's possible to get both so I'm a bit confused, because in the example he gives at the end to show this has the gradient of the root being negative.


Its only valid close to the root. So for the third one, the gradient is negative and less than one in magnitude close to the root (cobweb). But when you start further away where the gradient is positive, it looks like a staircase initially.
Original post by mqb2766
Its only valid close to the root. So for the third one, the gradient is negative and less than one in magnitude close to the root (cobweb). But when you start further away where the gradient is positive, it looks like a staircase initially.


Ahh so it's not solely determined by the gradient at the root, but also the gradient at the points on the curve. Is that right? And thank you.
Reply 3
Yes, the gradient at the root is local behaviour. It can do many things as you move significantly away.
Original post by dont know it
Ahh so it's not solely determined by the gradient at the root, but also the gradient at the points on the curve. Is that right? And thank you.

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