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I'm Bored, Post Me An Applied Math Question.


Renegade343
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Does this permit the use of a calculator?

If you wish.

 

I'd discourage the use of a calculator, if you can use completing the square or cross-factorisation.

 

If you'd rather use the quadratic formula or the equation function on a scientific calculator, that's fine by me too, although I'd prefer the former.

 

Thanks!

Edited by TheKingOfAllNoobs
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If you wish.

 

I'd discourage the use of a calculator, if you can use completing the square or cross-factorisation.

 

If you'd rather use the quadratic formula or the equation function on a scientific calculator, that's fine by me too, although I'd prefer the former.

 

Thanks!

I know the techniques, but if it permits the use of a calculator, then it would be easier.

Also, are there multiple answers to this? I did some quick checks on a bus ride, and there can be two solution sets.

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I know the techniques, but if it permits the use of a calculator, then it would be easier.

Also, are there multiple answers to this? I did some quick checks on a bus ride, and there can be two solution sets.

 

Answer: DON'T OPEN IF YOU HAVEN'T SOLVED IT YET

The answer is: x=12.

 

You can solve from there.

 

I know there is another answer, but just take the one with a whole number, reject the decimals.

 

And I need to know how you did it too.

 

Thanks!

Edited by TheKingOfAllNoobs
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Answer: DON'T OPEN IF YOU HAVEN'T SOLVED IT YET

The answer is: x=12.

 

You can solve from there.

 

I know there is another answer, but just take the one with a whole number, reject the decimals.

 

And I need to know how you did it too.

 

Thanks!

I saw the solution, compared it to mine, and found out that I made a very small error while squaring a number (as in: Only off by 0.2). But yes, I do know how to do it: 

 

First, write down these two equations (I wish Warframe Forums install LaTeX): 

 

(1/x) + (1/y) = 0.15

2x = y + 9

 

Modify the first equation to give you: 

 

(y + x)/xy = 0.15

y + x = 0.15xy

 

Then, substitute y = 2x - 9 (from second equation) into the first equation: 

 

2x + x - 9 = 0.15x * (2x - 9)

3x - 9 = 0.3x2 - 1.35x

0.3x2 - 4.35x + 9 = 0

 

We can then multiply 20 on both sides to obtain: 

 

20 * (0.3x2 - 4.35x + 9) = 20 * 0

6x2 - 87x + 180 = 0

 

Hence, we have solved part A. For part B, using the same formula we obtained earlier, we divide by 3: 

 

2x2 - 29x + 60 = 0

Then, using the quadratic formula (the one with x = (-b±√(b2 - 4ac)) ÷ 2a), we would obtain: 

 

x = 12, 2.5

 

Now, since you said to disregard the decimal value, I will only use x = 12: 

 

(1/12) + (1/y) = 0.15

1/y = 0.06666 (recurring)

y = 15

Positive difference between those two numbers: |12 - 15| (I use the modulus here so that no matter what number I subtract from, I will get a positive value) = 3. 

 

That should be your answer. 

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Yay thanks!

I only solved Part B, but I didn't know how to prove the equation...

I think I didn't do very well.

General rules for proofs (in which I am still practicing on them): 

  • Do not be afraid to introduce additional values when you need them, but remember to introduce values that would cancel out that additional value (e.g.: 0 can be written as 1 - 1). 

     

  • Look for established theorems, and use them as a building block for your proofs. 

     

  • Look for patterns. They tend to reveal paths to completing your proofs. 
Edited by Renegade343
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  • 2 weeks later...

Warframe should be thought at schools, I never saw so many kids doing good math because they deeply analyze how much a weapon or mod is improving/changing.

 

Anyway, i dont know any math problem for u to solve, but I know a few riddles:

 

The more I take, the more you have.

If I didn't take it, you wouldn't have any.

Negative numbers!

 

Do I win

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