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Sixth Form

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26 comments to Sixth Form

  • Grace Mullally
    December 24th, 2009 at 3:12 pm

    Hello!

    Show that e^(0.8x)- (1/3-2x)= 0 can be written as x = 1.5 – 0.5e^(-0.8x)

    I know I should be able to rearrange that.. but for some reason I can’t!
    Can you give me a nudge?

    Happy Christmas!

    Grace.

  • Mr Brewin
    December 24th, 2009 at 4:48 pm

    OK, so if you take the 1/(3-2x) over… then do the reciprocal of that, you should end up with
    3 – 2x = e^(-0.8x)

    Then should be able to do it from there?

    Well done revising Christmas Eve! Hope you take a break now!

  • Grace Mullally
    December 24th, 2009 at 7:40 pm

    After another 20 minutes of wobbling it around I see, yes.

    (just to be sure, you take the 2 out of 3-2x to give 0.5e^-0.8x = 1.5 – x then you’re at the answer after a bit of shuffling, right?)

    Wow. Hope I’m not that slow in the exam!

    Once I realised it was Christmas Eve I didn’t expect a reply at all – So thanks for helping!

    Have a Great Christmas!

  • Hannah S
    June 15th, 2011 at 6:16 pm

    Hi, got my C3 exam tomorrow and the only thing im finding difficult is probably the easiest thing which is finding the range and domain, so could you tell me how to do it please.

    An example from June 2010 is Find the range of g which is x2-4x+1?

    Thank you

  • Mrs Tibble
    June 15th, 2011 at 6:28 pm

    Hi Hannah,

    The input (x value) can be anything you like so the domain is R (the set of real numbers)

    The output, however, can’t be anything. Think about sketching the function (coincidentally I was doing this with my year 10s today!)
    It’s a quadratic function so you get a parabola (smiley because the x-squared term is positive)
    If you complete the square on that function, you get
    (x – 2)^2 -3
    so the minimum y value will be -3 (when the bracket=0)
    Therefore g(x) will always be greater than or equal to -3. That gives you the range.

    Hope that helps.
    Good luck for tomorrow
    :-)

  • Hannah S
    June 15th, 2011 at 6:40 pm

    Ok right get it…that has really helped! Ive been doing so much maths revision its unreal 4 exams i think it’s gonna be the death of me!
    Also i need quite a bit of help on c4 are you free on friday? if so would it be possible to go thorugh everything!

    Thank you Mrs T, c u tomorrow!

  • Mrs Tibble
    June 15th, 2011 at 6:58 pm

    Hi Hannah,

    Busy in 2 and 4, free in 1,3,5.
    JT

  • Becky
    September 3rd, 2011 at 8:09 pm

    Hiya Mrs Tibble,

    wow im the first person form my year to use the sixth form page :D ha ha. I was just wanting to ask you for an answer to one of the questions from the booklet to see if im along the right track. Im not too sure what i am doing on the surds question so was wondering if you have the answer to ex1G question 11. If not the question is…1 square root28 – 2 square root63 + square root7. Im just hoping i havent done them wrong :P Thank you :) Hope your having a good weekend :)

  • Mrs Tibble
    September 3rd, 2011 at 9:52 pm

    Hi Becky,

    Surds can only be combined if you are multiplying or dividing

    eg root18 x root2 = root(18×2) = root36 = 6

    You can NOT do this however if the surds are added or subtracted

    eg root3 + root4 is NOT root7

    In the question you have given here, the terms are added, and the only way this is possible is when the surd parts are the same. The smallest surd is root7 so try to turn them all into root 7s by using multiples of 7 for each surd:

    root 28 = root(4×7)
    root 63 = root(9×7)
    Notice that the numbers with the 7s are square numbers so can be brought out of the root sign:

    root28 = root(4×7) = 2root7 because the sq rt of 4 is 2.
    root63 = root(9×7) = 3root7

    thus rt28 – 2rt63 + rt7
    = 2rt7 – 6rt7 + rt7
    = -3rt7
    (think of the root7s as x for example so it simplifies like 2x-6x+ x = -3x)

    Don’t know if you needed all that detail or not, but hope you got it right :-)

    JT

  • Becky
    September 3rd, 2011 at 10:14 pm

    Aaaah thank you Mrs Tibble, I was on the right track just wasn’t sure how to simplify it but Rachel let me know how so i did it and got it right, yey! Yes thank you, the detail helped :)

  • Frances M
    September 4th, 2011 at 9:52 am

    Hey mrs T hope you’ve had a good summer. I was just wondering for ex 2D about completing the square, i dont know what sign to put in the brackets to get a minus.

    e.g. q5 how would you factorise xsquared -3x = 5
    thanksss

  • Mrs Tibble
    September 4th, 2011 at 1:38 pm

    Hi Frances,

    The sign in the bracket is the sign in front of the x term – otherwise you won’t generate a minus sign when you expand the bracket.

    The number to put in the bracket is half the x coefficient, so in Q5 it will be -3/2.

    Does that help?

    JT

  • Becky
    September 21st, 2011 at 4:40 pm

    I am doing Mr William’s homework corrections but I am stuck on Ex 2F question B, page 22.I’m not sure how to get the x axis intercept because I cant seem to factorize it. Am i meant to use the formula instead? :) Thank you

  • Mrs Tibble
    September 21st, 2011 at 5:18 pm

    Hi Becky,

    b^2 – 4ac = 9 – 40 which is negative so there are no roots. It doesn’t meet or cross the x axis.

    Tea Lady

    PS The answers are at the back of the book so look for clues there.

  • Becky
    September 21st, 2011 at 5:25 pm

    Hi Tea Lady, :D

    I thought of that but got a bit confused because if you multiply -5 and +2 you get -10 instead of +10?? Thank you again for today :)

  • Mrs Tibble
    September 21st, 2011 at 5:31 pm

    You’re welcome :-)

  • Mrs Tibble
    September 21st, 2011 at 5:35 pm

    Becky,

    If you complete the square with that one, you get (x – 1.5)^2 for the bracket bit.
    This would be zero when x=1.5 so this is how you know the dip is on the right of the y axis not the left.

    Mrs T

  • Becky
    September 21st, 2011 at 6:07 pm

    ooh okay I think I understand. Thank you :) Im sticking to your plan apart from one homework i couldn’t do at home so I started Mr William’s HW instead. :)

  • Mrs Tibble
    September 21st, 2011 at 6:24 pm

    Well done. It does help to break the jobs down and tick them off so you feel you’re achieving something and making progress. Shout out if you get stuck with the pure – I’m here for the duration marking the stats and year 8 books for tomorrow :-)

  • Becky
    September 21st, 2011 at 7:13 pm

    THANK YOU! Yes i will do, i might go and see Mr Williams tomorrow to go through the graphs, see how to draw them and make sure ive got them right. Aw poor you!! Well try and have a nice evening ha ha and thanks for the apple bar…very nice!! :D

  • Mrs Tibble
    September 21st, 2011 at 7:15 pm

    You seem quite chirpy for someone who is curve sketching ;-)
    Don’t stay up late – that’s part of your homework too remember 8-)

  • Becky
    September 21st, 2011 at 7:25 pm

    yes it does take quite a long time!! :P ha ha. No I’m off to bed in a minute, might have a cup of tea first and i will read my drama as planned :D

  • Mrs Tibble
    September 21st, 2011 at 7:31 pm

    Make one for me while you’re there!

  • Becky
    September 21st, 2011 at 7:33 pm

    ha ha ha!! aw yes make sure you have a cup of tea to keep you going through all that marking!! :D

  • Mrs Tibble
    September 21st, 2011 at 7:39 pm

    Yes Miss. Sleep tight!

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