01132014, 09:14 PM



Location: Northville, MI
11,882 posts, read 10,480,916 times
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Sorry. My bad . Slight Correction to my previous solution
Sum of the roots=(2+i)+(2i)=4
Product of the roots=(2+i)*(2i)=4(i)^2=4+1=5 (correction)
Quadratic equation 1=x^2+4x+5
Assume Quadratic equation 2=ax^2+bx+c
Multiplying we have
(ax^2+bx+c)*(x^2+4x+5)=x^4 +12x^3+27x^2+42x+56
Comparing coefficients:
x^4a=1
x^34a+b=12 therefore b=8
x^25a+4b+c=27 therefore c=27325=10
Hence, we need to solve x^2+8x10=0 to obtain the other 2 roots
Making use of the quadratic formula
x=(8+(64+40)^1/2)/2=(8+(104)^1/2)/2=4+((104)^1/2)/2
Other 2 roots are real:
x=4+((104)^1/2)/2
(or)
x=4((104)^1/2)/2

01132014, 09:45 PM



Location: Mt. Lebanon
1,793 posts, read 1,818,822 times
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Quote:
Originally Posted by fumbling
I think personal finance and learning about compound interest and staying out of debt and investing is far more practical than algebra. I think algebra is useless for 99% of students while 99% can benefit from personal finance math.

Depending on the job you do later on in life. The above example is the minimum example I can find. But in my mind algebra is basic thinking and it's like a way of training your mind to be logic. Same for trigonometry, which I use to love. Or geometry. it has to do with logic and being able to judge for yourself and being able to be good with your finances, investing and things like that (aka never go into debt, never go throu foreclosure etc) never having to deal with people to get you out of debt and things like this.

01132014, 09:51 PM



Location: Viña del Mar, Chile
16,416 posts, read 25,124,942 times
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Quote:
Originally Posted by LookingtoleaveFL
Anything algebra 2 and higher is pretty useless for most people. You're most likely never going to use quadratic equations or anything like that during your lifetime.

If you're doing anything close to technical related work, you will need algebra. Any type of marketing, business plans, accounting, economics.. all of these require calculus.

01142014, 08:19 PM



Location: Coastal New Jersey
50,926 posts, read 50,241,652 times
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Quote:
Originally Posted by charlygal
What you're calling "logic" is really algebra. If someone asked you how did you get that answer, what would you tell them? You have to be able to explain your "logic."
How would you teach this "logic?"
Also, that problem was fairly easy and used nice even numbers.

Ha, yes, that certainly helped!
I did explain my logic. (from Post 211: If she's ten years older than he is, the only possible time she's going to be twice as old as he is is when she's 20. So she's 19 now, and he's 9.). Doesn't need to be explained or taught because it just is something you know by looking at it.
But, as you said, that was an easy one.

01172014, 09:53 PM



338 posts, read 649,546 times
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Quote:
Originally Posted by burgler09
This cannot be serious.

Sorry, I know math is practical. I'm just looking for specific examples in which algebra is used.

01182014, 09:39 PM



Location: Northville, MI
11,882 posts, read 10,480,916 times
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Quote:
Originally Posted by Longhornsfan87
Sorry, I know math is practical. I'm just looking for specific examples in which algebra is used.

Analyzing profit, revenue, marginal revenue, and marginal cost knowing the nature of supply and demand within a particular company is a vital situation where Algebra in combination with calculus and data analysis is used.

01202014, 08:50 AM



338 posts, read 649,546 times
Reputation: 115


Quote:
Originally Posted by Adi from the Brunswicks
Analyzing profit, revenue, marginal revenue, and marginal cost knowing the nature of supply and demand within a particular company is a vital situation where Algebra in combination with calculus and data analysis is used.

In my marketing class, we talked about finding revenue, the break even point, etc.
But what about paying restaurant bills?

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