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Stuck on yet another maths question - please help Watch

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    I have gotten as far as:

    2(pi*r^2) + 2(pi*r*h) = (pi*r^2)h

    My problem is that I am struggling to rearrange the equation.

    Can somebody please help - it will be very much appreciated!
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    (Original post by knoxode)
    I have gotten as far as:

    2(pi*r^2) + 2(pi*r*h) = (pi*r^2)h

    My problem is that I am struggling to rearrange the equation.

    Can somebody please help - it will be very much appreciated!
    2*pi*r^2 + 2*pi*r*h = pi*r^2*h
    pi (2*r^2) + pi (2*r*h) = pi(r^2*h)
    Cancel off pi and take the two hs to on side. Then u'll find the solution
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    (Original post by stp2002)
    x
    Best not to provide full solutions, try to give nudges in the right direction instead. (see the posting guidelines)
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    (Original post by knoxode)
    I have gotten as far as:

    2(pi*r^2) + 2(pi*r*h) = (pi*r^2)h

    My problem is that I am struggling to rearrange the equation.

    Can somebody please help - it will be very much appreciated!
    First thing to do is look for stuff that's in all three of your terms, as you can then divide through by it and make the equation simpler. Can you see two values that appear in every term?
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    (Original post by sindyscape62)
    First thing to do is look for stuff that's in all three of your terms, as you can then divide through by it and make the equation simpler. Can you see two values that appear in every term?
    Pi is in all three terms!
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    (Original post by knoxode)
    Pi is in all three terms!
    Anything else? :-)
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    (Original post by simon0)
    Anything else? :-)
    Radius?
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    (Original post by knoxode)
    Radius?
    Great!

    Can you carry out what sindyscape62said and divide through by r and h?

    (Note as r and h are not zero, we can divide through).
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    (Original post by simon0)
    Great!

    Can you carry out what sindyscape62said and divide through by r and h?

    (Note as r and h are not zero, we can divide through).
    pi (2*r^2) pi (2*r*h) = pi(r^2*h)

    2r^2 2rh = r^2h

    r(2r 2h) = r^2h

    2r 2h = (r^2h)/r

    2r = ( r^2h)/r - 2h

    2r^2 = r^2h - 2h

    (2r^2) /r^2 = h - 2h
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    (Original post by knoxode)
    pi (2*r^2) pi (2*r*h) = pi(r^2*h)

    2r^2 2rh = r^2h

    r(2r 2h) = r^2h

    2r 2h = (r^2h)/r

    2r = ( r^2h)/r - 2h

    2r^2 = r^2h - 2h

    (2r^2) /r^2 = h - 2h
    Okay, a few things:

    - You are missing the addition signs.

    - On fourth line RHS, you can divide by r so to gain a term with "r" instead of "r^2".

    - On second from last line, it appears you attempted to multiply both sides by "r" but you did not multiply the last term by r.

    Start again and make "h" the subject.

    -------------------------------------------------------------

    So far we have:

     2 \pi r h + 2 \pi r^{2} = \pi r^{2} h,

     2h + 2r = rh, \quad by dividing by  \pi and r.

    Can you re-arrange to have h as subject?
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    (Original post by simon0)
    You are missing the addition signs.
    It's something with my phone - I can't put them in
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    (Original post by knoxode)
    It's something with my phone - I can't put them in
    No problem, can you take forward where I left?
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    (Original post by simon0)
    Okay, a few things:

    - You are missing the addition signs.

    - On fourth line RHS, you can divide by r so to gain a term with "r" instead of "r^2".

    - On second from last line, it appears you attempted to multiply both sides by "r" but you did not multiply the last term by r.

    Start again and make "h" the subject.

    -------------------------------------------------------------

    So far we have:

     2 \pi r h + 2 \pi r^{2} = \pi r^{2} h,

     2h + 2r = rh, \quad by dividing by  \pi and r.

    Can you re-arrange to have h as subject?
    2h + 2r = rh

    2h/r +2r/r = h


    I am very confused.
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    (Original post by knoxode)
    2h + 2r = rh

    2h/r +2r/r = h


    I am very confused.
    What you've got is correct. The question want h to be on its own, so next you need to get all the terms with h in them on the same side.
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    (Original post by sindyscape62)
    What you've got is correct. The question want h to be on its own, so next you need to get all the terms with h in them on the same side.
    That is the point at which I'm stuck :/
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    (Original post by knoxode)
    That is the point at which I'm stuck :/
    So what you've currently got is:

     2r+2h=rh

    Can you subtract one of the terms with h in it from both sides, which would make them both on the same side?

    As another example if you were given the equation:
     2x+5=8x
    would you know how to get x on its own in that?
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    (Original post by sindyscape62)
    So what you've currently got is:

     2r+2h=rh

    Can you subtract one of the terms with h in it from both sides, which would make them both on the same side?

    As another example if you were given the equation:
     2x+5=8x
    would you know how to get x on its own in that?
    2r + 2h = rh

    2h = rh - 2h

    2h = h(r-2)

    2h/h = r-2

    Sorry, making anything the subject is one of my weak points
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    (Original post by knoxode)
    2h + 2r = rh

    2h/r +2r/r = h


    I am very confused.
    at 2h + 2r = rh
    get h on one side
    2r = rh - 2h
    now try separating out h
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    (Original post by knoxode)
    2r + 2h = rh

    2h = rh - 2h

    2h = h(r-2)

    2h/h = r-2

    Sorry, making anything the subject is one of my weak points
    If so, then you should probably practice on a bunch of simpler questions before doing this one, because it's a really important skill.

    Your problem above is going from the first line to the second. Remember you're subtracting 2h from both sides. You've done this on the right side, but no on the left.
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    (Original post by sindyscape62)
    If so, then you should probably practice on a bunch of simpler questions before doing this one, because it's a really important skill.

    Your problem above is going from the first line to the second. Remember you're subtracting 2h from both sides. You've done this on the right side, but no on the left.
    2r + 2*h = r*h

    -2h

    2r = r - h
 
 
 
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