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Old 01-13-2014, 09:14 PM
 
Location: Northville, MI
11,882 posts, read 10,300,199 times
Reputation: 6312

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Sorry. My bad . Slight Correction to my previous solution

Sum of the roots=(2+i)+(2-i)=4
Product of the roots=(2+i)*(2-i)=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^4----a=1
x^3----4a+b=12 therefore b=8
x^2----5a+4b+c=27 therefore c=27-32-5=-10

Hence, we need to solve x^2+8x-10=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
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Old 01-13-2014, 09:45 PM
 
Location: Mt. Lebanon
1,766 posts, read 1,783,919 times
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Quote:
Originally Posted by fumbling View Post
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.
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Old 01-13-2014, 09:51 PM
 
Location: Viña del Mar, Chile
16,416 posts, read 24,813,977 times
Reputation: 16437
Quote:
Originally Posted by LookingtoleaveFL View Post
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.
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Old 01-14-2014, 08:19 PM
 
Location: Coastal New Jersey
49,618 posts, read 49,123,903 times
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Quote:
Originally Posted by charlygal View Post
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.
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Old 01-17-2014, 09:53 PM
 
338 posts, read 643,501 times
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Quote:
Originally Posted by burgler09 View Post
This cannot be serious.
Sorry, I know math is practical. I'm just looking for specific examples in which algebra is used.
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Old 01-18-2014, 09:39 PM
 
Location: Northville, MI
11,882 posts, read 10,300,199 times
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Quote:
Originally Posted by Longhornsfan87 View Post
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.
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Old 01-20-2014, 08:50 AM
 
338 posts, read 643,501 times
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Quote:
Originally Posted by Adi from the Brunswicks View Post
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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