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Terning a text based problem into a number based problem

  1. Jan 27, 2013 #1
    Turning a text based problem into a number based problem

    I can solve these types of questions such as:

    4(3x-5)=5x+2(x+15)

    but when a question is worded something like:

    "The second of three numbers is 1 less than the first. The third number is 5 less than the second. If the first number is twice as large as the third, find the three numbers."

    There is just too much going on in that worded problem for me to be able to express it differently.

    A simple question like:

    "A can of beans weighs twice as much as a can of coke plus 2lbs"

    This is simple, I can just say:

    b = 2c + 2

    But the questions in my book are just so long winded -_- any tips?
     
    Last edited: Jan 27, 2013
  2. jcsd
  3. Jan 27, 2013 #2
    Just take it slow and be systematic. The first clue you are looking for is how many variables are there - which is three. Then you assign them names, eg. a, b and c. Then just write down the equations as they come along. For instance, the first sentence also tells you that b=a-1, and so on.
     
  4. Jan 28, 2013 #3
    Re: Turning a text based problem into a number based problem

    You might want to choose names that you can't mix up part way through the problem.
    First step might be this, to avoid using x for first and then later x for second or third.
    Each sentence is turned directly into a single simple equation with appropriate names.

    second= -1+first
    third= -5+second
    first= 2*third

    Then if you need to the next step might be this

    s=f-1
    t=s-5
    f=2*t

    and solve that.

    When you get something like s=4, t=2, f=5 you can look back at your original problem and see exactly what each of those results should be used for.

    Just be careful to not mix up s and 5 or o and 0 or l and 1, etc.
     
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