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Edexcel maths question
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Htx_x346
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#1
Pls can i get some help with part b![Name: 538ABD8E-34C5-4143-B9FF-4FFF00D21C13.png
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Last edited by Htx_x346; 1 month ago
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Skiwi
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#2
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Driving_Mad
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#3
Htx_x346
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#4
(Original post by Skiwi)
Considering it's two marks you could just show what the two values give when used in the formula as you know what y value a should produce.
Considering it's two marks you could just show what the two values give when used in the formula as you know what y value a should produce.
(Original post by Driving_Mad)
Sub in y = 2, and x = 1.5 and 1.6. Should be a change of sign, so…
Josh Kelly.
Sub in y = 2, and x = 1.5 and 1.6. Should be a change of sign, so…
Josh Kelly.
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Driving_Mad
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#5
(Original post by Htx_x346)
Why would there be a change of sign since there isnt a root?
Why would there be a change of sign since there isnt a root?
Think back to what you have learnt in iteration
George Kambosos Jr.
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User3858395
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#6
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#6
(Original post by Htx_x346)
Why would there be a change of sign since there isnt a root?
Why would there be a change of sign since there isnt a root?
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Htx_x346
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#7
(Original post by Driving_Mad)
There isn’t a root as such, if there are solutions to f(x) = b, over a small interval, subbing in two values of x either side of the root would produce a change of sign of f(x) - b = 0, as long as the function is continuous.
Think back to what you have learnt in iteration
George Kambosos Jr.
There isn’t a root as such, if there are solutions to f(x) = b, over a small interval, subbing in two values of x either side of the root would produce a change of sign of f(x) - b = 0, as long as the function is continuous.
Think back to what you have learnt in iteration
George Kambosos Jr.
Still slightly confused about why it would produce a change of sign cause there isn’t a root, but ig ill just think about it
(Original post by User3858395)
But the question says ‘show there is a root’ so there is an assumed root.
But the question says ‘show there is a root’ so there is an assumed root.
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#8
My bad, for some reason I read that symbol as ‘root’. Maybe the sign change is down to a change in gradient. Best thing you can do at this stage is just learn and memorize how things are done. That’s what I do.
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mqb2766
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#9
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#9
(Original post by Htx_x346)
Oh yh i wasnt taught this topic
Still slightly confused about why it would produce a change of sign cause there isn’t a root, but ig ill just think about it
It doesn’t say that?
Oh yh i wasnt taught this topic
Still slightly confused about why it would produce a change of sign cause there isn’t a root, but ig ill just think about it
It doesn’t say that?
1.5^1.5 < 2 < 1.6^1.6
so ....
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Htx_x346
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#10
(Original post by mqb2766)
You know the function is increasing in that part of the graph and
1.5^1.5 < 2 < 1.6^1.6
so ....
You know the function is increasing in that part of the graph and
1.5^1.5 < 2 < 1.6^1.6
so ....
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Muttley79
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#11
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#11
(Original post by Htx_x346)
That makes sense but what does it really mean?
That makes sense but what does it really mean?
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mqb2766
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#12
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#12
(Original post by Htx_x346)
That makes sense but what does it really mean?
That makes sense but what does it really mean?
* The function is increasing.
* You know (can evaluate) 1.5^1.5 < 2 < 1.6^1.6 or f(1.5) < f(x) < f(1.6)
So what can you conclude about the point where f(x)=2?
Last edited by mqb2766; 1 month ago
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Htx_x346
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#13
(Original post by mqb2766)
It would probably be better for you to try and sketch whats happening.
* The function is increasing.
* You know (can evaluate) 1.5^1.5 < 2 < 1.6^1.6 or f(1.5) < f(x) < f(1.6)
So what can you conclude about the point where f(x)=2?
It would probably be better for you to try and sketch whats happening.
* The function is increasing.
* You know (can evaluate) 1.5^1.5 < 2 < 1.6^1.6 or f(1.5) < f(x) < f(1.6)
So what can you conclude about the point where f(x)=2?
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mqb2766
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#14
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#14
(Original post by Htx_x346)
Its between 1.5 and 1.6?
Its between 1.5 and 1.6?
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Htx_x346
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#15
(Original post by mqb2766)
Of course. The first part asked you to find the location of hte minimum (1/e) and to the right of the minimum, the function is increasing. You use that knowledge in this part to show the function must be equal to 2 somewhere between 1.5 and 1.6.
Of course. The first part asked you to find the location of hte minimum (1/e) and to the right of the minimum, the function is increasing. You use that knowledge in this part to show the function must be equal to 2 somewhere between 1.5 and 1.6.
Thank u
Last edited by Htx_x346; 1 month ago
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mqb2766
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#16
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#16
(Original post by Htx_x346)
That makes sense but why is the change of sign relevant in this case?
Thank u
That makes sense but why is the change of sign relevant in this case?
Thank u
g(x) = f(x)-2
as mentioned above. Then
g(1.5) < 0
g(1.6) > 0
so g() has a root somewhere between 1.5 and 1.6 which is the location where f()=2. Its the same argument.
Last edited by mqb2766; 1 month ago
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Htx_x346
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#17
(Original post by mqb2766)
Its similar to a root finding problem. Consider the function
g(x) = f(x)-2
as mentioned above. Then
g(1.5) < 0
g(1.6) > 0
so g() has a root somewhere between 1.5 and 1.6 which is the location where f()=2. Its the same argument.
Its similar to a root finding problem. Consider the function
g(x) = f(x)-2
as mentioned above. Then
g(1.5) < 0
g(1.6) > 0
so g() has a root somewhere between 1.5 and 1.6 which is the location where f()=2. Its the same argument.
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mqb2766
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#18
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#18
(Original post by Htx_x346)
What does () mean
What does () mean
In general, your responses are very terse and it would help for your replies to contain more content about what you do undersetand ...
Last edited by mqb2766; 1 month ago
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