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Some Math help!

Started by Lady Hitura Caprion, October 10, 2009, 01:44:47 PM

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Lady Hitura Caprion

I suck at algebra so far, pure and simple. Our teacher doesn't teach it right. So! Can someone check over these two equations and tell me if I'm doing quadratic functions right please?
Yes i did them in paint, they suck I know.

Oniya

That is the correct application, and your simplification (i.e., the actual math parts of it) looks correct as well.

(And for being done in Paint, you did a pretty clean job as well.  :D)
"Language was invented for one reason, boys - to woo women.~*~*~Don't think it's all been done before
And in that endeavor, laziness will not do." ~*~*~*~*~*~*~*~*~*~*~Don't think we're never gonna win this war
Robin Williams-Dead Poets Society ~*~*~*~*~*~*~*~*~*~*~*~*~*~Don't think your world's gonna fall apart
I do have a cause, though.  It's obscenity.  I'm for it.  - Tom Lehrer~*~All you need is your beautiful heart
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Oniya

#3
Looks right to me.  Another way to do it is to let Y=sqrt(x), which gives you y^2-5y-24 as your starting equation.  You just have to substitute back after you're done.
"Language was invented for one reason, boys - to woo women.~*~*~Don't think it's all been done before
And in that endeavor, laziness will not do." ~*~*~*~*~*~*~*~*~*~*~Don't think we're never gonna win this war
Robin Williams-Dead Poets Society ~*~*~*~*~*~*~*~*~*~*~*~*~*~Don't think your world's gonna fall apart
I do have a cause, though.  It's obscenity.  I'm for it.  - Tom Lehrer~*~All you need is your beautiful heart
O/O's Updated 5/11/21 - A/A's - Current Status! - Writing a novel - all draws for Fool of Fire up!
Requests updated March 17

Lady Hitura Caprion

Need help figuring out how to set up a problem since my teacher NEVER went over this with us and the book has no examples of it.

A boat travels 10 miles upstream and 10 miles downstream. The total time for both parts of the trip is 5 1/3 hours. The speed of the stream is 1 mph. What is the speed of the boat in still water?

Oniya

Have you covered systems of equations yet? (solving for two variables using two equations)
"Language was invented for one reason, boys - to woo women.~*~*~Don't think it's all been done before
And in that endeavor, laziness will not do." ~*~*~*~*~*~*~*~*~*~*~Don't think we're never gonna win this war
Robin Williams-Dead Poets Society ~*~*~*~*~*~*~*~*~*~*~*~*~*~Don't think your world's gonna fall apart
I do have a cause, though.  It's obscenity.  I'm for it.  - Tom Lehrer~*~All you need is your beautiful heart
O/O's Updated 5/11/21 - A/A's - Current Status! - Writing a novel - all draws for Fool of Fire up!
Requests updated March 17


Oniya

Actually, I think I was thinking too hard.  Distance = rate * time.  Rate = distance/time.  Time = Distance/rate.

16/3 (or 5 1/3) = 10/rate upstream + 10/rate downstream.
"Language was invented for one reason, boys - to woo women.~*~*~Don't think it's all been done before
And in that endeavor, laziness will not do." ~*~*~*~*~*~*~*~*~*~*~Don't think we're never gonna win this war
Robin Williams-Dead Poets Society ~*~*~*~*~*~*~*~*~*~*~*~*~*~Don't think your world's gonna fall apart
I do have a cause, though.  It's obscenity.  I'm for it.  - Tom Lehrer~*~All you need is your beautiful heart
O/O's Updated 5/11/21 - A/A's - Current Status! - Writing a novel - all draws for Fool of Fire up!
Requests updated March 17

Lady Hitura Caprion

Okay new one

How to do

(x +2)^3

I know it goes to

(x+2)(x+2)(x+2) but i dont know if i do two then the next or all three at once or what @.@

Oniya

Multiplication is associative.  (AB)C = A(BC) = (AC)B
"Language was invented for one reason, boys - to woo women.~*~*~Don't think it's all been done before
And in that endeavor, laziness will not do." ~*~*~*~*~*~*~*~*~*~*~Don't think we're never gonna win this war
Robin Williams-Dead Poets Society ~*~*~*~*~*~*~*~*~*~*~*~*~*~Don't think your world's gonna fall apart
I do have a cause, though.  It's obscenity.  I'm for it.  - Tom Lehrer~*~All you need is your beautiful heart
O/O's Updated 5/11/21 - A/A's - Current Status! - Writing a novel - all draws for Fool of Fire up!
Requests updated March 17

Lady Hitura Caprion

Factoring

x^5 - 3x^3 -8x^2 + 24 > 0

i know its factor by grouping buuut... I get as far as

x^3(x^2-3) -8(x^2+3) before I get lost...

Oniya

Remember that it takes two negatives to get a positive.
"Language was invented for one reason, boys - to woo women.~*~*~Don't think it's all been done before
And in that endeavor, laziness will not do." ~*~*~*~*~*~*~*~*~*~*~Don't think we're never gonna win this war
Robin Williams-Dead Poets Society ~*~*~*~*~*~*~*~*~*~*~*~*~*~Don't think your world's gonna fall apart
I do have a cause, though.  It's obscenity.  I'm for it.  - Tom Lehrer~*~All you need is your beautiful heart
O/O's Updated 5/11/21 - A/A's - Current Status! - Writing a novel - all draws for Fool of Fire up!
Requests updated March 17

Lady Hitura Caprion

xD no at that point i dont know what to do at ALL to further factor it!

Oniya

You have a slight mistake in your second grouping.  -8(3) = -24, not 24.
"Language was invented for one reason, boys - to woo women.~*~*~Don't think it's all been done before
And in that endeavor, laziness will not do." ~*~*~*~*~*~*~*~*~*~*~Don't think we're never gonna win this war
Robin Williams-Dead Poets Society ~*~*~*~*~*~*~*~*~*~*~*~*~*~Don't think your world's gonna fall apart
I do have a cause, though.  It's obscenity.  I'm for it.  - Tom Lehrer~*~All you need is your beautiful heart
O/O's Updated 5/11/21 - A/A's - Current Status! - Writing a novel - all draws for Fool of Fire up!
Requests updated March 17


Voichin

#15
Quote from: DarkReaperHituraCaprion on October 10, 2009, 07:33:31 PM


Oh my God, where does your maths teacher, no all your maths teachers since junior high, plus those in Chemistry, Physics and Computer science come from? Adeptus Inumeratus?

(x-5\sqrt(x)-24)^2=x^2-25x-24^2-2x5\sqrt(x)-2x24+2*5\sqrt(x)24. The rest you can do yourself, I hope.

You can't simply put square on each term of the sum - (1+1+1)^2=9 but 1^2+1^2+1^2=3! The general formula is as follows:

(a_1+a_2+....a_n)^2= a_1^2+a_2^2+....a_n^2+2a_1a_2+2a_1a_3+...2a_{n-1}a_n

You take all squares and add to them twice the product of every two terms!

Notable for bad manners and lack of empathy.

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Lady Hitura Caprion

typed out that equation is too confusing and hard to follow. I was following my book not my teacher in that anyway, I was absent that day o-o

Voichin

Hmmm, now tell me what is confusing you?
Notable for bad manners and lack of empathy.

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Lady Hitura Caprion

Its just hard to read in text assembled like that @.@

Voichin

#19
Put it in a tex editor and enjoy the magic :)

http://thornahawk.unitedti.org/equationeditor/equationeditor.php
Notable for bad manners and lack of empathy.

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Lady Hitura Caprion

1000 < 25t / 3t^2 + 15

"The population of a certain organism, in thousands, is given by the function P(t) = 25t / 3t^2 + 15, where t is time, in days. Find the interval on which the population is greater than 1000.

I know to set it up as:

1000 < 25t / 3t^2 + 15

then

0 < 25t / 3t^2 + 15 - 1000 aaaand then i blank

Oniya

Is the 15 in the denominator, or only the 3t^2?
"Language was invented for one reason, boys - to woo women.~*~*~Don't think it's all been done before
And in that endeavor, laziness will not do." ~*~*~*~*~*~*~*~*~*~*~Don't think we're never gonna win this war
Robin Williams-Dead Poets Society ~*~*~*~*~*~*~*~*~*~*~*~*~*~Don't think your world's gonna fall apart
I do have a cause, though.  It's obscenity.  I'm for it.  - Tom Lehrer~*~All you need is your beautiful heart
O/O's Updated 5/11/21 - A/A's - Current Status! - Writing a novel - all draws for Fool of Fire up!
Requests updated March 17


Vekseid

The equation gives the population in thousands - not individuals. Trying to solve it for 1000 is nonsense because

25t/3t^2 = 8.33333/t - the population is steadily reducing from an infinity at zero. It never rises.

What you are looking for is to solve t in 0 = 25t/3t^2 + 15 - 1

Oniya

It still makes a difference whether the initial equation is 25t / (3t^2 + 15)
or 25t / (3t^2) + 15
"Language was invented for one reason, boys - to woo women.~*~*~Don't think it's all been done before
And in that endeavor, laziness will not do." ~*~*~*~*~*~*~*~*~*~*~Don't think we're never gonna win this war
Robin Williams-Dead Poets Society ~*~*~*~*~*~*~*~*~*~*~*~*~*~Don't think your world's gonna fall apart
I do have a cause, though.  It's obscenity.  I'm for it.  - Tom Lehrer~*~All you need is your beautiful heart
O/O's Updated 5/11/21 - A/A's - Current Status! - Writing a novel - all draws for Fool of Fire up!
Requests updated March 17