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Pre-Algebra

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Fri Jan 23, 2009 3:17 am
Evi says...



So, yeah. Math has never been my strong point, and my parents are about as skilled as I am. I tremble at the sight of these problems. They're a piece of cake for you smart people, but my twelve-year-old mind is too tired to think straight.

9m-7m-5=17

Is there a property I should be using to simplify this?

And...

3t + 5
--------- = -5
8


Ick. Any help in showing a poor seventh grader the steps?

EDIT:

I have new problems! These first two, thanks to Jared and Snoink, are taken care of. Now, I've got word problems.

Anyone care to help me unravel them?

[s]There are two trees in a yard. One of them is 50 inches tall and grows at a rate of 2 inches per month. The other tree is 59 inches tall and grows at a rate of 1 inch per month. How many month will it take until both trees reach the same height?[/s] Solved. Thanks to Random.Thoughts, who rocks epically.

-And-

Roses cost $15 for a dozen, or more in bought individually. You want to purchase 9 dozen and 6 individual roses for a party decoration. For the price of 9 dozen and 6 individual roses you can also purchase 51 individual roses. How much is one rose? How much money do you have to spend on the party decoration?


I would be able to do these if I new exactly which equation to use. How should I phrase it? They, obviously, have variables. I think each problem has two of the same variable, like two x's or two h's, but not an x and an h. If that makes any sense.

Help? I'll be forever grateful to you brilliant word-problem decipher-ers.

~Evi
Last edited by Evi on Sun Feb 01, 2009 10:55 pm, edited 5 times in total.
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Fri Jan 23, 2009 6:17 am
Snoink says...



Haha, for a second, I thought they were really two variables! :o

First off, I don't know what you mean by this:

3t + 5
--------- = -5
8


Can you express it any other way? :?

For your first one:
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Fri Jan 23, 2009 1:19 pm
BigBadBear says...



3t + 5
--------- = -5
8

First thing you're going to do is multiply the 8 from the denominator (bottom number on a fraction and from the -5, because what you do to one side, you do to the other.

3t + 5
--------- = -5 x 8
[s]8 x 8[/s]

Now your problem looks like this:

3t + 5 = -5 x 8 --> 3t + 5 = -40

Now you subtract a five from both sides:

3t + 5 - 5 = -40 - 5

And you end up with: 3t = -45

Then you divide the three on both sides:

3t = -45/3
-
3

And then
t = -45/3. I don't know what the answer is, cause I don't have my calcutator here, and it's 6 in the morning.

But, viola!

-Jared
Just write -- the rest of life will follow.

Would love help on this.




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Fri Jan 23, 2009 9:12 pm
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Evi says...



Eureka!

You both rock epically. I'm humbled by your genius. And, sorry, I though there were two variables. But I was tired, and my brain wasn't working properly. I think those were the only ones giving me trouble, but I might come across another...

Thanks again!
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Fri Jan 23, 2009 11:25 pm
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Snoink says...



Lol, no problem!

And Jared, you're lame.

-45/3 = -15

You don't need a calculator for that. Just look at a clock! XD
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"The mark of your ignorance is the depth of your belief in injustice and tragedy. What the caterpillar calls the end of the world, the Master calls the butterfly." ~ Richard Bach

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Sun Feb 01, 2009 2:38 am
Evi says...



*Bump*

Hopefully, bumping is allowed in this forum. If it's not, please forgive me. I just didn't want to start a whole new thread.

The new problems I need help with are in the original post.
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Sun Feb 01, 2009 7:07 pm
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random.thoughts says...



Ok, the first one is easier then it seems! I'm going to do a general overview of the problem and if you need it more in dept then just PM me.

The first tree is 50in tall already. And it grows at a rate of 2x. (x=time in months) So the equation of growth with the tree would be 50+2x. The original height plus how much it could grow. The same is true for the second tree. 59< original hight. plus 1x (x=time in months). 59+1x. To find when the would be the same hight (hint hint equal to each other) just have the equations equal each other.

50+2x=59+1x
x=9
9 months.




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Sun Feb 01, 2009 10:55 pm
Evi says...



Ugh! That was simple. I'm just mathematically challegned, Random.

I still need help on the second one, if anyone can help me decipher it!
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Tue Feb 03, 2009 11:22 pm
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Snoink says...



For the rose problem, consider this:

You are given that one dozen roses cost $15. So let's let d (for dozen) = 15.

(Recap: d = 15)

For individual roses, you aren't given a price. That is our variable. Let individual rose = i (for individual!)

(Recap: one individual rose = i)

Now, you know that if you buy nine dozen roses plus six individual roses, it's the same thing as buying 51 individual roses. So:

9d + 6i = 51i

EXCEPT! We know d, which is 15. So:

9*15 + 6i = 51i

...you should be able to figure out the rest. :)
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Fri Apr 10, 2009 8:11 pm
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chasingcolts21 says...



They pretty much told you everything, but if you need any more help, I specialize in Algebra :P Feel free to PM me.

It's super easy to me. :D
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