Sorry Rachel, you got here before me!!
|
||||||
Auto Draft148 comments to Year 11 Div 1 sign in here please |
||||||
|
Copyright © 2012 The Sydenham High School Mathematics Department Blog - All Rights Reserved |
||||||
|
||||||
Auto DraftSorry Rachel, you got here before me!! 148 comments to Year 11 Div 1 sign in here please |
||||||
|
Copyright © 2012 The Sydenham High School Mathematics Department Blog - All Rights Reserved |
||||||
Thank you!
Oh and also..I REALLY don’t understand how to solve simultaneous equations. I have the CGP Guide for Maths and it has equations with a quadratic but in the past paper it has 2??
How do I solve…
y = x-6
x2 +y2 =26
Also me and Fran were wondering we have to know about vectors because we both don’t have a clue what they are :/
Ahhhh maths revision is so stressful!
Hi Rachel,
CHILL!! That’s an order.
We haven’t done vectors yet so ignore them!
We also haven’t done simultaneous equations where one is a quadratic.
But if you really want to know:
Replace the y-squared in the 2nd equation with (x-6)^2 from the first.
Now you have an equation with only x’s in it
Square the bracket and tidy it all up with all terms on left and zero on right.
All terms are even so make life easier by halving everything.
Factorise.
Solve.
Ahhhhhhhh ok….I won’t worry about that then
And also….is there an answer scheme going up for practice paper D?? Thanks
Rachel,
This is far too late to be doing maths!!!!
Waiting for one of the men to find the mark scheme for the paper!! Don’t hold your breath!
Now go to bed – or watch a dvd, or do something more fun than late-night-maths.
See you tomorrow!
JT
Hi Mrs Tibble
Hope you had a good Christmas- just read the comments about vectors, simultaneous equations and I’ve revised these topics without realising that we hadnt covered them yet- so are they not coming in the exam? and I don’t understand what ‘dimensional analysis’ means?- Thankyou!
Hi Fatima,
We did dimensions on November 10th if you look in your book. Saying you can’t recognise what we’ve covered and not covered is a statement likely to land you in hot water!!!! I didn’t say we hadn’t covered simultaneous equations – just the ones where one is a quadratic.
JT
Year 11 – some answers to the practice paper:
1. 120 deg, 28deg, angles in quad. sum to 360
2. 1 and a half, stopped, 27
3. 0.67359116, 0.67
5. -4, 3/5
6. 47.1
7. (6,5)
8. £1.73
9. £3.30
10. 5.6 (make sure you have done the last step correctly)
11. -3 -2 -1 0 1, x>5
13. Can’t tell as total numbers aren’t given
14. 8, m^2+7m+10
15. 157.7
17. 12
18. 3.86 x 10^7, 1.73 x 10^-2
19. 98deg
20. 2a(4ax + 7y), (w-3)(x+y)
21. (14n + 10m)/24
22. 77.6deg
23. missing from table 29, 6
24. £16919
25. 2n+1
26. 0.777
27. x=5,y=-1 and x=1,y=-5
hey Mrs T,
Happy New Year..
thanks for the answers to paper D. I am stuck on a few of the asnwers:
- Solve 9a+5=4a+8
- for trial and improvement I can not find anywhere with the method (column headings) you should use??? I got the answer but in a few of the other practice papers i have not had the correct headings.
Thanks
and also what is the formula for working out the area of and arc sector.
Thank you
Hi Frances,
Happy New Year to you too
9a+5=4a+8
Separate letters and numbers (remember change side, change sign)
9a – 4a = 8 – 5
Simplify:
5a = 3
Divide by 5:
a = 3/5
Trial and improvement:
3 columns headed ‘Try’ ‘put the expression you are subbing into here’ ‘Comment’
For arc length and sector area, work out what fraction of the circle you have by doing angle at centre / 360
then it’s that fraction of the full circle.
Have fun,
JT
ohhh….so for trial and improvement do you not have a column for the answer you get when you try the value??
thankss
Hi Frances,
It goes in the middle – which is where you show all the working out.
Have a look here
http://studymaths.co.uk/keytopics/trialandimprovement.html
Mrs T
ohhh ok…
thanks
i get it now
hi miss sorry for intruding on your class blog but for qu 2 does the answer have to be exactly 27 minutes? if so why
dont worry worked out what that was referring to
okay im stuck on factorise completely wx + wy – 3y – 3x
Hi I am really stuck on question 6 on the revision questions because it says 6. The probability that I will win a game of football is 0.6 What is the probability that I will not win a game of football? But I am not quite sure on what the probability scale is.
The probability scale goes from 0 to 1.
A probability of zero means that the result is impossible – it won’t happen.
Rolling a ten on a normal dice is impossible and has a probability of 0.
A probability of 1 means that it is a certainty – it will definitely happen.
The sun coming up tomorrow has a probabiltiy of 1.
Think about the question again – “The probability of winning is 0.6″
Remember that 0.6 is 6/10. This means that there are 6 chances out of 10 that they will win.
So what is left over? Those 4 remaining chances are the ones where they don’t win. So 4 out 10 is the probability of not winning.
Your answer is 4/10 or 0.4
MW
Ok thankyou
Hi Mr Williams, I am stuck on 2f, 5a, 5b and 7b. On 7b I don’t know what the shape is so I can’t work it out. On 5a and 5b I don’t remember you teaching us that but maybe I was just away when you did it. Thanks.
Hi Anya,
Yes 27 for Q2 because of the accuracy asked for in the question.
Factorising:
rearrange to wx-3x+wy-3y
=x(w-3) + y(w-3)
Common factor now is bracket:
(w-3)(x+y)
JT
Rebecca – can you let me get back to you in a bit.
MW
Rebecca, to answer your questions:
2f) 3 – - 9 means 3 take away negative 9
Taking away a negative number means that you need to add. Think of it as if in normal life, as opposed to maths, you are taking away something bad. This makes things better or nore positive!
So 3 – - 9 becomes 3 + 9 which is 12
5a) and 5b)
Have a look at the bit on the homepage where I had put the link for the questions. In the responses bit, I typed out how to do those ones.
7b)The shape is a trapezium. To find the area draw a line to split it diagonally – you will form two triangles. Then find the areas of these two triangles. Finally add them up to get the area of the trapezium.
There are some examples of this in the link to the answers from the lesson. Again this link is right by the link for the homework questions.
I do hope that this helps.
MW
Hi Mr williams, i stuck on 7b. I know its a trapizium i don’t know how to work it out.
oh sorry, i know the answer now.
Mrs T…is there anything in the non-calculator section that we definately won’t need for the calculator exam? or is the calculator paper literally based on EVERYTHING :/
Just seeing how much time and stuff I need to go over it
Thanks
Hi Rachel,
They don’t tend to repeat specific topics so if you had a question on it today, there probably won’t be one on the 2nd paper. Obviously more general sort of stuff will reappear.
However, the topics you know you need a calculator for are almost certain to be there: trig, stuff with pi, questions which say ‘use your calculator’. You can generally do a pretty good prediction based on that.
Does that help?
JT
Sorry it’s taken me a while to get back…
OK I don’t really remember much on the non-calculator but I suppose I’ll just skim over everything that uses a calculator after college on Saturday
Also, is it like normal exams where we just get our exams back normally in class because I know history were being given out but I think that might just be because our module is next Friday? And also people were saying how you can get your predicted grades somehow? Sorry I’m dumping all of this on you but you’re quite organised so you probably know
Hi Rachel,
You get your papers back in your first maths lesson after mocks.
JT
Heyyyy,
Can you send me a link to the edexcel past papers site or something (for calculator) because i don’t know how to find them.
Thanks
Don’t worry I found the page. sorry
oh and for working out the area of a triangle (trig. way) when it says the sin of c would that give you one of the lengths of the triangle?? thanks
Hi Frances,
Don’t understand your question!
Area = 0.5 ab sinC
so to find area you would need 2 sides and the angle between them.
JT
ok thanks i get it, usually, using the formula, you just ‘insert’ the values.
I did a practice paper and was wondering:
-for trial and imrpovement, when it says to one dp and the ‘correct’ value has 2 d.p’s do you round up or down, i rounded up and in the mark scheme it was rounded down.
-and there was a question where you had to calculate the length of a side within a compound shape, is that vectors, or something we haven’t done? I couldn’t find any notes on it.
Thankksss
Hi Frances,
For trial and improvement let’s say you’ve worked out that x=3.5 is too small and x=3.6 is too big. This tells you that x lies between 3.5 and 3.6.
The last calculation you do then is halfway: 3.55.
If this is too small, then x lies between 3.55 and 3.6 – so 3.6 to 1dp
If this is too big, then x lies between 3.5 and 3.55 – so 3.5 to 1dp.
Is that OK now?
Length of side question: not sure what you mean. Can you tell me where it’s from?
JT
Ohhh…thank you I get it! That other question was from a practice paper and I though it was vectors because the lines had those arrows on them! Does that mean its vectors??
Thanks
Hi Frances,
Yes, lines with arrows are vectors!! We haven’t done them yet.
JT
hey…
I don’t understand, for the homework, how you get questions 1 and 2 into quadratic format?????
e.g q1) xy = 3, y = x – 2.
I’ve got up to the stage you showed us in class but don’t know what to do next!? Thanks
Hi Frances,
2 ways you can do this – one slightly easier than the other.
1) rearrange 1st equation to give y=3/x or x=3/y and sub in to other one (harder as you need to get rid of the denominator)
2) easier: replace the y in the first equation with (x-2) to give x(x-2)=3. Multiply out the bracket which will give you a quadratic equation. Move the 3 over so you have =0 and then solve for x.
Have fun
Mrs T
ohhhh thank youu…
also, for the next one i’ve tried the ‘harder’ method but i don’t know how to get id of the denominatorr???
xy = 2
2y – x =3
Hi Frances, to get rid of fractions, multiply every term by the denominator. So if you’ve subbed in x=2/y, multiply every term by y; if you’ve subbed in y=2/x, multiply every term by x.
JT
okk thankss i’ll try it
Hey Mrs T, also for the last question i ended up with x squared – 2, which is difference of 2 squares…but how is this put into brackets???? (if it can be??)
Thanksss
Hi Frances,
You should have x-squared – 1 = 0 which is easy to put into brackets as 1 is square.
In answer to your other question, if you have a non-square number, use surds:
(x – root2)(x + root2)
JT
Ohhh yeahh my baddd..Thanksss again mrs T
how do you work out the volume of a square based frustrummm?????
*frustum
Hi Frances,
Look at the diagram. What was the shape before the top was cut off?
What shape has been cut off?
Answer those and you’ll be able to do it.
JT
but the question only includes a measurement of the bottom shape’s heighttt?? not the height of the whole shapee??
But the words tell you that the top HALF is cut off.
Ohhhhhhh…rightt thankss