C34 Math IAL 16/6 June 2014

[Ayesha B]

hey guys help me out with no6 part b in this paper https://eiewebvip.edexcel.org.uk/Reports/Confidential Documents/1006/6665_01_que_20100615.pdf

i never understood how to graph f (lxl ) :/

to plot f(|x|),

Delete everything that has -x coords (everything on the left side of the Y axis)
Take whatever you have on the positive side (right side of the Y axis) and reflect it in the y axis.

 

[Hasan Naqvi]

to plot f(|x|),

Delete everything that has -x coords (everything on the left side of the Y axis)
Take whatever you have on the positive side (right side of the Y axis) and reflect it in the y axis.

wow thats very helpful, thanks alot

 

[Ayesha B]

In that specific paper itll look like a W,
y -intercept (0, 5)
Minimum points (3, -4) and (-3, -4)

 

[Ayesha B]

wow thats very helpful, thanks alot

No problem

 

[Hasan Naqvi]

ohoh. one last question, check out no8 c
https://eiewebvip.edexcel.org.uk/Reports/Confidential Documents/1201/6665_01_rms_20120307.pdf

why did they take 2pi - theta?

 

[urwahboy]

check out part c... the graph should have the min at (-3,2) i dunno why is the ms shpowing 0,0?

 

[Hasan Naqvi]

cause its f(lxl) - 2. shifted 2 units down.

 

[Ayesha B]

check out part c... the graph should have the min at (-3,2) i dunno why is the ms shpowing 0,0?View attachment 45422 View attachment 45423

yeah because its translated down 2 units!

 

[urwahboy]

if it shifts two units down then the point at -3,0 will also shift 2 units down

 

[Ayesha B]

ohoh. one last question, check out no8 c
https://eiewebvip.edexcel.org.uk/Reports/Confidential Documents/1201/6665_01_rms_20120307.pdf

why did they take 2pi - theta?

umm wait lemme look at the qp as well

 

[Ayesha B]

if it shifts two units down then the point at -3,0 will also shift 2 units down

The point (-3, 0) isnt part of the f(|x|) graph because it has -x coords

 

[Ayesha B]

ohoh. one last question, check out no8 c
https://eiewebvip.edexcel.org.uk/Reports/Confidential Documents/1201/6665_01_rms_20120307.pdf

why did they take 2pi - theta?

Okay I know why

You need to go back to your CAST diagram

In the ALL quadrant you'll have your related angle i.e. your first solution

But if you think about it, everytime you solve for theta, you look at the other quadrant its in as well right?

Because tan is positive its gonna be in the first and third quadrant, where the solution is pi + the related angle


Soooo it will be pi + (pi - theta) and therefore (2pi - theta)

 

[urwahboy]

The point (-3, 0) isnt part of the f(|x|) graph because it has -x coords

I dont understand what you are trying to say .. it is part of f(x) right? then it will be part of f(|x|) too...
from what i have studies in the book first we will reflect it in y axis then we will transform it 2 units down

 

[Ayesha B]

That was an interesting and diff question!

 

[urwahboy]

to plot f(|x|),

Delete everything that has -x coords (everything on the left side of the Y axis)
Take whatever you have on the positive side (right side of the Y axis) and reflect it in the y axis.

ist it the reflection on x axis?

 

[Ayesha B]

I dont understand what you are trying to say .. it is part of f(x) right? then it will be part of f(|x|) too...
from what i have studies in the book first we will reflect it in y axis then we will transform it 2 units down

No no no okay listen...

When you have to plot f(|x|),

You delete the parts on the left side of the y axis,
and then you reflect whats on the right side of the y axis in the y axis...


Okay listen, if you have the Keith Pledger C3 book, go to p. 82 and look at point 3

 

[Ayesha B]

ist it the reflection on x axis?

Nope, for |f(x)| its reflection in the x-axis
For f(|x|) its reflection in the y axis
But they still work a little differently

 

[Ayesha B]

urwahboy did you get it? :/

 

[urwahboy]

urwahboy did you get it? :/

yep thank you so much ... since one year i was studying it all wrong :/ actually they never gave an example of f(|x|) they gave the examples of |f(x)| .. i thought both are same... once again thanks

 

[Ayesha B]

yep thank you so much ... since one year i was studying it all wrong :/ actually they never gave an example of f(|x|) they gave the examples of |f(x)| .. i thought both are same... once again thanks

Loool! Glad I could help