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Type: Posts; User: kristo

1. Question: Trig proof

by kristo
3
Views
972

Yes, the angles were restricted to the first...

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 :).
2. Question: Trig proof

by kristo
3
Views
972

trig proof

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...
3. Question: Some geometry stuff

by kristo
0
Views
292

Some geometry stuff

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.. ...

by kristo
4
Views
1,215

.. what?
5. Question: Maths

by kristo
3
Views
3,100

Let's make a quadratic function of this, x being...

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 +...
6. Question: I need a few tips

by kristo
1
Views
1,300

I need a few tips

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...
7. Question: Some root equations

by kristo
7
Views
1,815

I think I got it now. \frac{sqrt{a+x}+...

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}=...
8. Question: Some root equations

by kristo
7
Views
1,815

You're fast lol, I just noticed the mistake and...

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.
9. Question: Some root equations

by kristo
7
Views
1,815

Thanks a lot Galactus, I've solved some of the...

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} -...
10. Question: Some root equations

by kristo
7
Views
1,815

Some root equations

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 + \sqrtx}{sqrt x - \sqrtx}=3
11. Question: Factor Completely

by kristo
3
Views
2,157

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

(a^2-b^2) = (a-b)(a+b)
ye
12. Question: A word problem

by kristo
3
Views
3,734

Okie, thanks a lot Capuchin ;)

Okie, thanks a lot Capuchin ;)
13. Question: A word problem

by kristo
3
Views
3,734

A word problem

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...
14. Question: A word proble m

by kristo
7
Views
1,206

S being the distance person A walked until...

S being the distance person A walked until meeting.
The distance between town A and B is s + s + 6 which is 30km.
15. Question: A word proble m

by kristo
7
Views
1,206

I think I solved it.. \{...

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
16. Question: A word proble m

by kristo
7
Views
1,206

No, they are starting from different towns,...

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...
17. Question: A word proble m

by kristo
7
Views
1,206

A word proble m

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...
18. Question: Angles

by kristo
3
Views
3,989

Thanks a lot ;)

Thanks a lot ;)
19. Question: Angles

by kristo
3
Views
3,989

Angles

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

by kristo
2
Views
1,138

21. Question: Trigonometry, simplifying

by kristo
2
Views
1,138

Trigonometry, simplifying

How do I simplify this?
1-2sin a * cos a
free cookies for anyone who helps!
22. Question: A thingy

by kristo
4
Views
1,029

So it's (x-y)(x+y) and after replacing...

So it's (x-y)(x+y) and after replacing (a^2-b^2)(a^2+b^2)?
Thanks a lot, appreciate it!
23. Question: A thingy

by kristo
4
Views
1,029

A thingy

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)
24. Question: An equation

by kristo
13
Views
2,290

This is the exercise: Find two numbers, if...

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...
25. Question: An equation

by kristo
13
Views
2,290

Well, let's keep practicing then :D Or not.....

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...
26. Question: An equation

by kristo
13
Views
2,290

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

Thanks a lot, I think I'll be able to do it now :)
27. Question: An equation

by kristo
13
Views
2,290

What are you talking about?:confused: lol Did...

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.
28. Question: An equation

by kristo
13
Views
2,290

An equation

\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
29. Question: 2 maths exercises

by kristo
3
Views
1,886

Thanks! So is it 12h for the first one and 1.5h...

Thanks!
So is it 12h for the first one and 1.5h for the 2nd exercise?
30. Question: 2 maths exercises

by kristo
3
Views
1,886

2 maths exercises

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...
31. Question: Some geometry stuff

by kristo
3
Views
1,358

Okie, thanks a lot :).

Okie, thanks a lot :).

by kristo
3
Views
1,358

33. Question: Some geometry stuff

by kristo
3
Views
1,358

Some geometry stuff

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...
34. Question: Some physics stuff

by kristo
2
Views
928

Water can be 0C without turning into ice. Still...

Water can be 0C without turning into ice.
Still help needed!
35. Question: Some physics stuff

by kristo
2
Views
928

Some physics stuff

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...
36. Question: Balancing a bar

by kristo
9
Views
1,085

I think I got it now, thank you :). Sorry about...

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

by kristo
9
Views
1,085

I understand it for most of the part, but could...

I understand it for most of the part, but could you explain the x/2 and x/6 part a bit?
38. Question: Balancing a bar

by kristo
9
Views
1,085

So, x is about 1.5 meters, right?

So, x is about 1.5 meters, right?
39. Question: Balancing a bar

by kristo
9
Views
1,085

Thanks a lot for your help! I get this far, but...

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
40. Question: Balancing a bar

by kristo
9
Views
1,085

Balancing a bar

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...
41. Question: Oxidation, reduction

by kristo
5
Views
3,367

So Fe is reductant, as he loses 3 electrons?

So Fe is reductant, as he loses 3 electrons?

by kristo