math

Discussion in 'Math' started by mozikluv, Apr 13, 2005.

  1. mozikluv

    Thread Starter AAC Fanatic!

    Jan 22, 2004
    1,437
    1
    hello everybody,

    how about refreshing the mind of an old cow on how to solve this algebraic equation? solve for x

    (12-x/5) - (x/5) = 0.835

    pls. show the step by step procedure

    mucha mucha gracias
    :D :D :D
     
  2. Firestorm

    Senior Member

    Jan 24, 2005
    353
    0
    welp here goes lol :)
    (12-x/5) - (x/5)=0.835
    first you have to get x by itself on one side or the other.
    You probly know the saying Please excuse my dear aunt sally (order of operations)
    not really sure on your (12-x/5): Is just x over 5 or is everything(12-x)/5?
    I am going to work this out assuming it is all over 5
    first move (x/5) over to the right side of the = mark by adding it to both sides.
    heres your eqn. now:
    (12-x/5)=0.835+(x/5)

    Now get rid of the fraction (5) on the left side by multiplying it to both sides
    5(12-x/5)=5(0.835)+5(x/5)--->just showing the setup
    (12-x)=4.175 + x
    no need for parenthesis anymore now :)
    12-x=4.175+x
    add x to the right side
    12=4.175+2x
    subtract 4.175 from both sides
    7.825=2x
    divide by 2
    3.9125
    :)
    If it is the other way around I will work it out 2 if you need me 2
    does this recall old math classes? lol ;)
    btw-still working understanding the transistor array moz, will try to update it shortly :D
    thx l8er

    -fire
     
  3. mozikluv

    Thread Starter AAC Fanatic!

    Jan 22, 2004
    1,437
    1
    hi,

    now why didn't i think of that "to get x by itself on one side or the other" maybe am getting too much cholesterol in my brain
    :D :D :D

    thanx mucho mucho B) firestorm
     
  4. Firestorm

    Senior Member

    Jan 24, 2005
    353
    0
    np lol :lol:
    alg 1 finally payed off :p
    thx l8er

    -fire
     
  5. pebe

    AAC Fanatic!

    Oct 11, 2004
    628
    3
    No, multiplication or division is always done first, before adding or subtracting, unless the + or – term is enclosed within brackets. So the first part of the equation is 12 minus one-fifth of x.

    Now subtracting the second term (again one fifth of x) gives 12 minus two fifths of x, for left hand side of the equation. Now multiply by -1 to change all the signs, to -12 +2/5 = -0.835

    Take the -12 across and change the sign, then 2x/5 = -0.835 + 12 (= 11.165)
    Cross multiplying the 5 simplifies to 2x = 11.165 * 5 (= 55.825)

    So x = 27.9125
     
  6. Firestorm

    Senior Member

    Jan 24, 2005
    353
    0
    yes, thats if the answer for the 1st way :)
    The only reason it might be the other way is if he forgot to put the () aound it all since the fraction is at an angle. It shows the method though ;)
    thx l8er

    -fire
     
  7. mozikluv

    Thread Starter AAC Fanatic!

    Jan 22, 2004
    1,437
    1
    hi,

    thanx pebe for additional input for the problem that i have presented. actually i had the answer or the value of "X" which is 3.91 rounded off. it's just i don't know how the answer was arrive at. Firestorm solved it and he got the same answer, likewise a newly graduate engineering student passed by the house and i also ask him to solve it for me and he also got the same answer.

    :D moz
     
  8. pebe

    AAC Fanatic!

    Oct 11, 2004
    628
    3
    Hi Moz. If you got the answer 3.91 then it was not the answer to the equation you had shown.

    The '/' symbol, in the context of a formula or equation, means 'divided by' and the usual mathmatical rules apply.
     
  9. Firestorm

    Senior Member

    Jan 24, 2005
    353
    0
    yea, you have to be careful how you write eqn's. To get 3.91 you have to include everything over 5 in the 1st 1 by (). ;)
    thx l8er

    -fire
     
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