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Yes, the angles were restricted to the first quadrant, forgot to add it in the first post, sorry!
Thanks for your help, I got it now :).

Hey, how do I prove this inequality?
sin(a+b)<sin a + sin b
If I write out the sin(a+b) I get this:
sin a cos b + sin b cos a - sin a - sin b<0
But I got no idea, what to do next.
Any help...

I'm supposed to find the blue colored surface area in both tasks.

1 The radii of the circles are 3 cm and 1 cm, I have no idea what to do here lol.. ...

.. what?

Let's make a quadratic function of this, x being the number of bottles sold. Money he gets from selling wine is price per bottle*bottles sold.
f(x)=5*10000 + x(5-0,0002x)
f(x)=-0,0002x^2 + 5x +...

Here's the problem:
A bicycler and a car driver started driving towards each other from towns A and B.
After they had drove for an hour the car driver sped up by 20 km/h. If the car wouldn't have...

I think I got it now.

\frac{sqrt{a+x}+ sqrt{a-x}}{sqrt{a+x}-sqrt{a-x}}=sqrt{b}
First I multiply both sides by sqrt{a+x} - sqrt{a-x} \\
Then I get sqrt{a+x}+sqrt{a-x}=...

You're fast lol, I just noticed the mistake and was going to edit my post
I'll try to do it again, going to post later if I get the solution.

Thanks a lot Galactus, I've solved some of the equations now, still need help with others.

\frac{sqrt{a+x}+ sqrt{a-x}}{sqrt{a+x}-sqrt{a-x}}=sqrt{b}
First I divide both sides by sqrt{a+x} -...

Hey, I need some help with solving x for these equations:
1 x^2-4x+6=sqrt{2x^2-8x+12}


2 \frac{x}{x+1} -2 \frac sqrt{x+1}sqrt{x}=3


3 \frac{sqrt x + \sqrt[3]x}{sqrt x - \sqrt[3]x}=3

(a^2-b^2) = (a-b)(a+b)
ye

Okie, thanks a lot Capuchin ;)

A pool is filled by two pipes. It takes the first pipe 2 hours more and the second pipe 4 hours more to fill it than both pipes at the same time.
The book says that the first pipe fills the pool in...

S being the distance person A walked until meeting.
The distance between town A and B is s + s + 6 which is 30km.

I think I solved it..
\{ \frac{s}{v_1}=\frac{s+6}{v_2} \\ \frac{s}{v_2}=4 \\ \frac{s+6}{v_1}=9
Which solves for s=12, v1=2, v2=3

No, they are starting from different towns, person A from town A is going to town B and person B from town B going to town A, they meet on the way.
So person A arrived at town B 4 hours after...

Here it is:
Two persons started moving towards the other town at the same time, when they met, one person had walked 6 kilometers more than other person. After meeting they continued walking towards...

Thanks a lot ;)

How do I find the angles x and y here?
http://img338.imageshack.us/img338/2773/matenurk001vz2.jpg

Thanks for your help, here's some cookies ;)

How do I simplify this?
1-2sin a * cos a
free cookies for anyone who helps!

So it's (x-y)(x+y) and after replacing (a^2-b^2)(a^2+b^2)?
Thanks a lot, appreciate it!

I need help with solving this one.. How do I factor the a^4-b^4?
\frac{a^4-b^4}{4a^2+4b^2} : (a+b)

This is the exercise:
Find two numbers, if multiplied they equal 3 times their sum; sum of both numbers squared is 160.
I hope I worded it correctly.

Oh and I go to 9th grade, so it's primary...

Well, let's keep practicing then :D

Or not.. lol

I tried it your way asterisk, but got stuck again.
Got this far:

(\frac{3y}{y-3})^2+y^2=160 \\
\\
\frac{9y^2}{y^2-6y+9}+y^2=160 \mid...

Thanks a lot, I think I'll be able to do it now :)

What are you talking about?:confused: lol

Did it in latex now, I tried to do it before, but forgot to add the math tags lol.
Oh and yeah, they're supposed to be simultaneous.

\left\{x*y=3x+3y\\x^2+y^2=160} \right\ \\

x=(\frac{3x+3y}{y}) \\

(\frac{3x+3y}{y})^2 +y^2=160 \\

\frac{9x^2+18xy+9y^2}{y^2}+y^2=160 \mid *y^2 \\
9x^2+18xy+9y^2+y^4=160y^2

Thanks!
So is it 12h for the first one and 1.5h for the 2nd exercise?

1. A pipe fills a pool in 4 hours, another pipe drains a full pool in 6 hours. How long will it take to fill the pool if both pipes are opened?

2. A pool is connected with 3 pipes. Two pipes fill...

Okie, thanks a lot :).

Anyone please?

A trapezoid's parallel sides are 8 decimeters and 18dm, the other sides are 8.1dm and 5dm.
How do I find surface area and height of the trapezoid? We're studying trigonometry at the moment, but I...

Water can be 0C without turning into ice.
Still help needed!

I need help with 2 exercises.

Quarter of whole work was done with a machine, which' power is 4kW,
then a new machine was taken into use.
The whole work was done with 6kW power.
1. What was...

I think I got it now, thank you :).
Sorry about the half comment, accidentally pressed F5 while writing it and can't edit.

I understand it for most of the part, but could you explain the x/2 and x/6 part a bit?

So, x is about 1.5 meters, right?

Thanks a lot for your help!
I get this far, but don't really know what to do next, a little help, please?
http://img68.imageshack.us/img68/2365/geilord9kl.gif

On one end of a 6m bar there is a 600kg weight, on the other end there's a 200kg weight, the bar itself weighs 20kg.
Where shall the point of support be so that the bar is balanced?

I hope you...

So Fe is reductant, as he loses 3 electrons?

Fe2O3 + 3H2 -> 2Fe + 3H2O

Which materials are reductants, which are oxidants?
Please explain the solution, too. Any help is appreciated :).