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# P2 Question!! watch

1. Help needed in solving this Question!!

Rep will be given!! Thanx for Help!!
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2. Can anyone do this question?
3. Can do this sequence question???/ REALLY in DESPERATE NEED OF HELP!!!
4. Sorry I can't help much here as I can barely read most of it.

Anyway for part a) you need to substitute the values of 1 and 2 into the funtion, one should be positive and one should be negative. This indicates the root is between 1 and 2.

For part b) simply substitute in the value of x1 into the iterative function and it will produce the value of x2 do this again for x3 and so on.
5. well part (c) says this :

By considering the change of sign of f(x) in a suitable interval. verify that your answer to part (b) is correct to 3dp (2 marks)
6. (Original post by Steve8052)
well part (c) says this :

By considering the change of sign of f(x) in a suitable interval. verify that your answer to part (b) is correct to 3dp (2 marks)
Ok, what they want you to do is use the same method as part a) to show that your answer to part b) is correct.

So if your answer for x4 was for example purposes only, 1.436 then substitute in the values 1.4355 and 1.4365 into the original function f(x) and you should see a sign change.

Hope that helps.
7. its like this, there is a theory that for if f(a) > 0 and f(b) <0 then a root of f(x) lies between a and b. I can't remember what it is called but use that and solve the question
8. (Original post by himurakenshin)
its like this, there is a theory that for if f(a) > 0 and f(b) <0 then a root of f(x) lies between a and b. I can't remember what it is called but use that and solve the question
Sign change method.
9. Thanks a lot guys REP for ALL!! hehe but in days time!!! ive alredy given rep 2day!
10. For part (b),
x0=1.5
and i found that x1=1.387, x2=1.396, x3=1.395, x4=1.395.

The questions asks me to find values for x1, x2, x3 and x4 and find an approximation for the root. I only got 1 mrk out of 4 here. Does anyone know where I went wrong and lost the other 3 marks?
11. (Original post by Steve8052)
For part (b),
x0=1.5
and i found that x1=1.387, x2=1.396, x3=1.395, x4=1.395.

The questions asks me to find values for x1, x2, x3 and x4 and find an approximation for the root. I only got 1 mrk out of 4 here. Does anyone know where I went wrong and lost the other 3 marks?
I'm guessing you must of done the calculations wrong and come up with the wrong values of xn+1. I'd also suggest using a few more d.p. than 3 as that is what the final answer will be in.

By the way each value (i.e. x1, x2 etc) are all approximations of the root and they gain accuracy as they progress. So that x4 would be your final answer.
12. Thanks a lot!!

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