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Mrs Tibble’s Year 11209 comments to Mrs Tibble’s Year 11 |
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Hi Mrs Tibble,
Im not sure how you work out the perpendicular distance of the line AD on question 11b.!!!
Hi Sam,
Can you tell me which paper it is please as I forgot to bring one home!
Thanks
JT
Paper 3 Non Calculator
Lol Sam! A year would be really useful
Actually is it the question about the area of a parallelogram? If so, that perpendicular distance is the height of the parallelogram if you turn it round so the sloping side becomes the base. You have base x ht = area, and area is already known from the first part of the question.
If it’s not that question, you’ll need to give me the info!
Have fun,
JT
Mrs T ! There are two non calculator maths papers called Paper 3
but one says ‘specimen paper’ and the other says ‘Monday 19 May 2008-morning’
Which one is it :O ?
Btw, don’t worry Mrs T i have already done lots of revision before this paper!
Hi Idil, thanks for the info.
Do them both – the more the merrier!! The one Sam is talking about is the 08 paper I think. Are you OK or do you want some help?
JT
yes that’s the one miss, thank you!
Hi Mrs Tibble! Didn’t really know where to put this! Sorry, I’m really stuck on the maths h/w, the surds sheet.. I’m not sure how to do question 6. Thanks
Hi Aggie,
This will probably be too late now! Sorry – it was 6th form prizegiving tonight so I was at school.
Surds can only be added if they are the same surd so that is your clue as to what to aim for. The first one is root 5 and the second is root 20 so try turning the root 20 into a root 5 surd so that you can add them.
Do the same kind of thing for (b) – turn them both into root 7s
In (c) you’ll have to change them both so look at what they have in common.
JT
Hi Mrs Tibble, I ‘m a bit confused on the homework because i got to the stage where you either have to factorise or you use the formula. I can’t seem to factorise and I’ve tried all the possibilities so is it correct to use the formula? the equations is: 10x^2 – 8x – 8 = 0
Hi Zoe,
Your x term is wrong – look at the brackets again.
JT
When you’ve sorted that out, it still doesn’t factorise.
Okay thank you!
hi I am really confused on question 3 for the homework i’m not quite sure what to do because i got to x^2+(x-7)^2=29 then i made that x^2+x^2+7x+7x+14=29 what do I have to do next? Or is that completely wrong? thanks
Hi Sophie,
You’ve gone wrong squaring the bracket. Do it separately and watch the signs (first mistake). Second is 7×7 isn’t 14 lol! Sort that out then tidy it up – everything on the left = 0. All nos even so halve to make life easier. It factorises nicely.
Good luck!
JT
ok thank you. i’ve got x^4-14x+20=0, can i halve the x^4 ?
Hi Sophie,
You shouldn’t have x^4.
x^2 + x^2 = 2x^2
Powers only change when you multiply (or divide)
JT
I’m really stuck on the corrections from the penultimate homework that you set.
The equation is y= x^2-3x+5
y= 2x-1
I’m not sure when I subsitute the second equation into the first if it makes
2x-1=x^2-3x+5 and if it does, whether i need to move the = to the other side and you do this. I know the change side, change sign rule but I’m not sure which of the numbers will change sign. Thank you
Hi Ella,
Yes, you have combined the 2 equations correctly. The x^2 term is positive so collect everything on that side of the = leaving 0 on the other. Tidy it up, factorise, solve and then get the y values. Should be straightforward now: you’ve done the hardest bit
Come back again if you get stuck.
JT
Oh so if you tidy the first bit up does it make
2x-1+x^2-3x+5=0?
Hi Ella. No. The 2x-1 has crossed the = to join the other terms so these signs should have changed.
Oooh so does that make it
2x+1+x^2-3x+5=0?
You’ve made the 1 positive but you haven’t made the 2x negative.
Oh so -2x+1+x^2-3x+5=0?
Yes. Now tidy it up.
x^2-4x+5=0?
x^2 is fine!
-2x and -3x doesn’t make -4x
1 and 5 doesn’t make 5
oh woops is it x^2-2x+6=0
The 6 is correct lol!
What does -2 and -3 make Ella?
oh no i mean x^2-5x+6=0
YAY! 3rd time lucky
Now factorise it!
For the answer I’ve got (2,3) (3,5) is that right?
BINGO
Well done!
Thank you for all your help!
You’re welcome
Now go and do something easy – like a French essay
For the tan graph that we have to do, for the y axis you said that it has to go demo 1-12 do you mean 0.1 because the number are to small for 1/2/3
Hi Zoe,
No, I meant what I said in class. The first values are very tiny, but further along they get very big.
JT
Ohhhh okay, thank you!
hi, im a bit confused on the tan graph because i have some really random values for thingslike tan(90, tan(180) and tan(300)
Tan 90 isn’t defined – I told you that in class!!
Tan 180 is zero
Tan 270 isn’t defined but tan 300 should be fine
Tan 360 is zero too.
ok thank you i switched calculators and got completely different results that make abit more sense now
Did you check the calculator was in degree mode before you started?
I’m really stuck on how to work out 2b. I don’t understand how we’re meant to use the things that we learnt in the lesson to draw that line of the graph
Hi Ella,
Do you want it linked to the function notation?
The graph you sketch for part a is your starting point for reference: this is the original function. You can replace the x^2 with f(x) if it helps. You don’t need it after part a as it’s only there to give you a curve to move around.
So for (a) sketch y=x^2 but label it y=f(x)
(b) then becomes y=3f(x)+2
(c) is y=f(x)-3
(d) is y=0.5f(x)+1
All of these transformations affect the curve in the y direction only – the same as the ones we did in the lesson.
Hope that helps.
Mrs T
I understand renaming the graph y=f(x) but for b I don’t know how to make it 3f(x)+2 because of the plus two on the end of the equation, you have to move the equation up two squares on the page but I’m not sure how you would put the 3 at the beginning to make it 3f(x)
Hi Ella,
The 3 at the front means all the y values are 3 times bigger – we did one in class but I used 2 not 3 so they doubled there.
You can do the 2 stages one at a time if you like:
first do the x3 stretch
then slide it up the page 2 places.
JT
Hi, I am trying to do question 2 in the homework but i’m not sure where to begin? Thanks
Hi Sophie,
They tell you that the equation of the transformed curve is
y = a – b cos(kt)
(t is what they have used instead of x because if you look at the axis , it’s called the t axis)
Start with the cos bit because that’s telling you the original graph would have been y = cos(t)
Now look at what they have drawn and work out how it is different from a normal cos curve. There are 4 differences, each one matching up with the letters and a sign change.
Good luck!
JT
Ok thank you! I’ll have a try