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Maths numerical methods

https://imgur.com/a/11dwP9b

Could someone help me with the above question please, parts b and d?

For part b I don’t know how to find the starting value, but I know f’’(x) is zero as it is a point of inflection. I feel like I should use the third formula because b is positive and that would give me a positive value but I’m not sure how to justify that?


For part d again I don’t know what value of a I should start with but I know how to sub it into the formula and stuff.

Reply 1

Original post by username79352
https://imgur.com/a/11dwP9b
Could someone help me with the above question please, parts b and d?
For part b I don’t know how to find the starting value, but I know f’’(x) is zero as it is a point of inflection. I feel like I should use the third formula because b is positive and that would give me a positive value but I’m not sure how to justify that?
For part d again I don’t know what value of a I should start with but I know how to sub it into the formula and stuff.

Cant see the pic on imgur.

Reply 2

Reply 3

Original post by username79352
https://imgur.com/a/11dwP9b
Could someone help me with the above question please, parts b and d?
For part b I don’t know how to find the starting value, but I know f’’(x) is zero as it is a point of inflection. I feel like I should use the third formula because b is positive and that would give me a positive value but I’m not sure how to justify that?
For part d again I don’t know what value of a I should start with but I know how to sub it into the formula and stuff.

The second derivative is
30x^4 + 6x - 14
and you want to find the root. A simple guestimate using a couple of simple values for x should give you an upper/lower bound which contains a sign change and hence a rough starting value?

Same for d?
(edited 3 weeks ago)

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