ffs I got the maximum turning point wrong.. (1 Viewer)

[jamesfirst]

Can I get 1 mark if I did it wrong ?

 

[damo_g]

It might depend where you stuffed up. You might have had to get the correct factorisation and put it equal to zero. How did you show it was a max if you got the wrong value?

I don't know what happens on the graph, could lose a mark for not having the correct turning point. If your point doesn't make it any easier to graph, then you could get 2 for that one, providing you graphed your answer right?

 

[MrBrightside]

You actually do turning points in 3 unit. lol Is it possible for a 2 unit student to do? or is the question much harder than a 2 unit version? what was the question?

 

[damo_g]

You actually do turning points in 3 unit. lol Is it possible for a 2 unit student to do? or is the question much harder than a 2 unit version? what was the question?

A decent 2 unit student could do it.

f(x) = e^-x - 2e^-2x

Had to find f '(x), the max turning point, the x and y intercepts, what the graph did as x approached infinity, and then graph it.

That was for 8 marks. Pretty generous question 4.

 

[SpiralFlex]

You actually do turning points in 3 unit. lol Is it possible for a 2 unit student to do? or is the question much harder than a 2 unit version? what was the question?

Yes, there are a few additions to trigonometry differentiation though.

 

[MrBrightside]

A decent 2 unit student could do it.

f(x) = e^-x - 2e^-2x

Had to find f '(x), the max turning point, the x and y intercepts, what the graph did as x approached infinity, and then graph it.

That was for 8 marks. Pretty generous question 4.

Oh wow, what question would it be in? Q1 -7. I think I've done a similar question to this in past papers.

 

[jamesfirst]

A decent 2 unit student could do it.

f(x) = e^-x - 2e^-2x

Had to find f '(x), the max turning point, the x and y intercepts, what the graph did as x approached infinity, and then graph it.

That was for 8 marks. Pretty generous question 4.

I don't know how but I got the y-intercept as the turning point...


maybe I used f(x)............ god DAMNIT

 

[x3mattyboii]

Was the maximum turning point at like (-1.2x, -28) ? Because the y intercept was all the way at the top? And i was like "this doesnt look right"

 

[MrBrightside]

I don't know how but I got the y-intercept as the turning point...


maybe I used f(x)............ god DAMNIT

ahaha it happens. It's best to set out your work neatly for these questions and don't rush. Because a simple early error can lead to a fatal answer and you will have to do the whole question again to get the right points etc.

 

[jamesfirst]

dude. I put maximum as the y intercept and I was like... wtffffffffffffffff

 

[Riproot]

dude. I put maximum as the y intercept and I was like... wtffffffffffffffff

Yeah I mixed them up on the graph. :/

 

[MATHSCAPE]

do you have to show that it's a max? :|

 

[SpiralFlex]

Was the maximum turning point at like (-1.2x, -28) ? Because the y intercept was all the way at the top? And i was like "this doesnt look right"

Let

















When

Don't forget to test too.

 

[Nympha]

Was the maximum turning point at like (-1.2x, -28) ? Because the y intercept was all the way at the top? And i was like "this doesnt look right"

I think the turning point was (ln4, 1/8)
The y intercept was -1.

do you have to show that it's a max? :|

I assume that you'd usually have to. f'(x)=0 does not automatically mean it's a max. point. It could be a minimum or a horizontal point of inflexion or whatever for all you know.

 

[michaeljennings]

I think the turning point was (ln4, 1/8)
The y intercept was -1.


I assume that you'd usually have to. f'(x)=0 does not automatically mean it's a max. point. It could be a minimum or a horizontal point of inflexion or whatever for all you know.

You dont have to show its a max because the question says its a max already

 

[Nympha]

You dont have to show its a max because the question says its a max already

Ah, okay I couldn't remember what the question said and I cbf to look it up. I stand corrected.

 

[michaeljennings]

Ah, okay I couldn't remember what the question said and I cbf to look it up. I stand corrected.

haha no worries =)

 

[SpiralFlex]

You dont have to show its a max because the question says its a max already

I was taught to show it even though it says maximum. Either that or it must be a habit.

 

[HyperComplexxx]

I was taught to show it even though it says maximum. Either that or it must be a habit.

Same here, i was taught to show it regardless the mark allocated to that question

 

[michaeljennings]

Same here, i was taught to show it regardless the mark allocated to that question

mmm yeah thats what our teachers tell us but id be surprised if they took marks off cos the question says "f(x) has one maximum turning point, find the coordinates of the turning point" and when you solve f'(x) you only get one possible x value that solves f'(x) = 0 so it would be fair to assume that it is the maximum turning point the question is referring too