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logs - c2

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    hi can someone tell me please the formula if you need to make the same log bases such as logbase3(2-3x)=logbase9(6x2-19x+2)

    how would i make the same bases 3 what is formula thanks
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    (Original post by otrivine)
    hi can someone tell me please the formula if you need to make the same log bases such as logbase3(2-3x)=logbase9(6x2-19x+2)

    how would i make the same bases 3 what is formula thanks
     \displaystyle log_ab = \frac{log_cb}{log_ca}

    Example 1:

     \displaystyle log_39
    If we want to make it to the base 5.
     \displaystyle log_39 = \frac{log_59}{log_53}

    Example 2:

     \displaystyle log_37
    We want to convert it to the base 7.
     \displaystyle log_37 = \frac{log_77}{log_73} =\frac1{log_73}
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    (Original post by raheem94)
     \displaystyle log_ab = \frac{log_cb}{log_ca}

    Example 1:

     \displaystyle log_39
    If we want to make it to the base 5.
     \displaystyle log_39 = \frac{log_59}{log_53}

    Example 2:

     \displaystyle log_37
    We want to convert it to the base 7.
     \displaystyle log_37 = \frac{log_77}{log_73} =\frac1{log_73}
    one question p=logbaseq16 how can you make the base q subject?
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    log_a(b) = c


    b = a^c


    a = b^{\frac{1}{c}} = \sqrt[c]{b}
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    (Original post by TenOfThem)
    log_a(b) = c


    b = a^c


    a = b^{\frac{1}{c}} = \sqrt[c]{b}
    do we need to know that for c2 cause i am solving this one where it says
    p=logbaseq16 find in terms of P
    a)logbaseq2
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    (Original post by otrivine)
    do we need to know that for c2 cause i am solving this one where it says
    p=logbaseq16 find in terms of P
    a)logbaseq2
     p=log_q16

    Remember,  16 = 2^4

    Example:

     p=log_m4
    You are asked to find  log_m2 in terms of p.

    So here is how we will do it,
     log_m2 = log_m\sqrt4 = log_m4^{\frac12}= \frac12 log_m4.
    We know log_m4 equals  p so we can write  \frac12 log_m4 as  \frac12 p
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    (Original post by otrivine)
    one question p=logbaseq16 how can you make the base q subject?
     p=log_q 16

    To make it the subject, use the rule,  log_a(b) = c can be written as  a^c =b

    Compare,  p=log_q 16 with  log_a(b) = c .
    Here,  p= c \ \ q=a \ \ 16 = b

    So now write it in the way  a^c=b , sub in the above data, we will get,  q^p = 16

    Now to remove the power of  p from  q , follow the following step:
     q^p = 16 \\ q^{p \times \frac1p} = 16^{\frac1p} \\ q = 16^{\frac1p}
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    (Original post by otrivine)
    do we need to know that for c2
    It is the core definition of logs


    (Original post by otrivine)
    cause i am solving this one where it says
    p=logbaseq16 find in terms of P
    a)logbaseq2

    A Raheem said this does not require anything beyond knowing that 2^4 = 16
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    (Original post by TenOfThem)
    It is the core definition of logs





    A Raheem said this does not require anything beyond knowing that 2^4 = 16
    thanks and last question ten of them this question
    http://www.edexcel.com/migrationdocu...e_20110526.pdf

    8)a) to do that how ? i got 2xpower3 for volume then what i do?
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    (Original post by otrivine)
    thanks and last question ten of them this question
    http://www.edexcel.com/migrationdocu...e_20110526.pdf

    8)a) to do that how ? i got 2xpower3 for volume then what i do?
    Let 'm' be the other side of the cuboid.

    Remember,  \text{Volume} \ = 2x \times x \times m

    We know volume equals 81, find an equation for 'm'.

    L = 4(2x) + 4x +4m
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    (Original post by raheem94)
    Let 'm' be the other side of the cuboid.

    Remember,  \text{Volume} \ = 2x \times x \times m

    We know volume equals 81, find an equation for 'm'.

    L = 4(2x) + 4x +4m
    yep got the answer thanks and why did u put m and not x
    ANd for C2 what volume and lengths and area do we need to know to be able to apply like these questions?
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    (Original post by otrivine)
    yep got the answer thanks and why did u put m and not x
    ANd for C2 what volume and lengths and area do we need to know to be able to apply like these questions?
    How do you know the other length will be 'x'?

    Another length is specified as 'x' so i should now choose a different variable.

    Just learn the formulas given in the book, to be honest, this part a of the question was o-level stuff.
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    (Original post by raheem94)
    How do you know the other length will be 'x'?

    Another length is specified as 'x' so i should now choose a different variable.

    Just learn the formulas given in the book, to be honest, this part a of the question was o-level stuff.
    thanks you are the best
    but i did not get the question on logs where we said let p=logbaseq16 find in terms of p logbaseq2?
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    (Original post by otrivine)
    thanks you are the best
    but i did not get the question on logs where we said let p=logbaseq16 find in terms of p logbaseq2?
    I don't have any idea of explaining you without doing a solution, so i will have to go for it.

     p=log_q 16 = log_q2^4 = 4log_q2 \implies \dfrac{p}4 = log_q2

    So  \boxed{ log_q2 = \dfrac{p}{4} }

    You look to be posting a lot, so i think you should consider learning LaTex.
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    (Original post by raheem94)
    I don't have any idea of explaining you without doing a solution, so i will have to go for it.

     p=log_q 16 = log_qi2^4 = 4log_q2 \implies \dfrac{p}4 = log_q2

    So  \boxed{ log_q2 = \dfrac{p}{4} }

    You look to be posting a lot, so i think you should consider learning LaTex.
    thanks ok http://www.edexcel.com/migrationdocu...e_20090605.pdf
    question 9)a) i did h=300/2r
    and sub into the the area but is not working?
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    (Original post by otrivine)
    thanks ok http://www.edexcel.com/migrationdocu...e_20090605.pdf
    question 9)a) i did h=300/2r
    and sub into the the area but is not working?
    You need to work hard on your basics mate.

     A = \frac12 r^2 \theta = \frac12 r^2
     V = A \times h
    We know V= 300, find 'h' in terms of r^2.

    Then find the surface area, i am assuming you are clear with the meaning of surface area.
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    (Original post by raheem94)
    You need to work hard on your basics mate.

     A = \frac12 r^2 \theta = \frac12 r^2
     V = A \times h
    We know V= 300, find 'h' in terms of r^2.

    Then find the surface area, i am assuming you are clear with the meaning of surface area.
    how can i improve my basics for C2 please tell me raheem

    what does A and H stand for in volume
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    (Original post by otrivine)
    how can i improve my basics for C2 please tell me raheem

    what does A and H stand for in volume
    There is no magic wand to improve yourself.

    I just used to read all the examples and solve all the questions from the book.

    A stands for area.

    The 'H' is 'h', and it is labelled in the diagram.
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    (Original post by raheem94)
    There is no magic wand to improve yourself.

    I just used to read all the examples and solve all the questions from the book.

    A stands for area.

    The 'H' is 'h', and it is labelled in the diagram.
    shall i do all the mixed exercise?
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    (Original post by otrivine)
    shall i do all the mixed exercise?
    :yep:

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