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# C3 June 05 Question watch

1. 4d) By considering the change of the sign f'(x) in a suitable interval, prove that a = 0.1443 correct to 4 decimal places.

I have found f'(x) =

How do I do part 4d?

I know I need to subs 2 values and if one result is positive and one is negative, there will be a root. How do I know which 2 values to sub in?

Thank you
2. (Original post by gottastudy)
4d) By considering the change of the sign f'(x) in a suitable interval, prove that a = 0.1443 correct to 4 decimal places.

I have found f'(x) =

How do I do part 4d?

I know I need to subs 2 values and if one result is positive and one is negative, there will be a root. How do I know which 2 values to sub in?

Thank you
the 2 intervals would be
0.14435 and 0.14425
3. (Original post by Egyptianglue.)
the 2 intervals would be
0.14435 and 0.14425
They are...how do you know that though?

Thanks for your help. Are they +/- by 0.0005?

If this is the case that they are +/- by 0.0005, then for another question, how would I identify the 2 intervals?
4. what are these homo boards you guys do? weird questions....
5. (Original post by gottastudy)
They are...how do you know that though?

Thanks for your help. Are they +/- by 0.0005?

If this is the case that they are +/- by 0.0005, then for another question, how would I identify the 2 intervals?
the max and min that would be rounded to this number! if u get what im sayin!
6. (Original post by gottastudy)
4d) By considering the change of the sign f'(x) in a suitable interval, prove that a = 0.1443 correct to 4 decimal places.

I have found f'(x) =

How do I do part 4d?

I know I need to subs 2 values and if one result is positive and one is negative, there will be a root. How do I know which 2 values to sub in?

Thank you
It's asking you to do it for 4 decimeal places so use boundries.

0.1443-(0.0001/2)<x< 0.1443+(0.0001/2)

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