I'd like co-ordinate geometry to be in there and  Matrices and financial mathematics

Alan, why did you separate differential equations from calculus?

what is the difference between game theory and probability?

maybe statistics and probability could be separated.

Where would we put surds and sequences and series?

Could we also introduce difficulty levels?  This would be especially relevant for topics like algebra. 

All just ideas.

I forgot to put that in there.  The starting temp is 150 degrees

There is missing information here. We need the dimensions of these rooms.

I'm happy kitty u liked that one!! I'm seeing u after a very long time!!

and your welcome Melody!

I think we need to know what temperature the coffee is at presently.

"of" can be interpreted as multiplication, so we have:

2/3 * q = 14        ---Divide both sides by 2/3

q = 14 ÷ 2/3       ---To divide a fraction, multiply by the reciprocal (in other words, flip the fraction) 

q = 14 * 3/2

q = 42/2

q = 21

Hi Melody, Hi Alan,

good idea. let's see what topics will be suggested.

available math sub category topics:

Just arrived on this website, and this problem just appeared to me. So here is the answer : 

The first machine has been bought $1000. Each year, due to the depreciation, 10% of the value of the machine has to be deducted then to summurise : 

Year 1 = 1000

Year 2 = 1000 - 10% = 1000 - 100 = $900

Year 3 = 900 - 10% = 900 - 90 = $810

Year 4 = 810 - 10% = 810 - 81 = $729

Year 5 = 729 - 10% = 729 - 72.9 = $656.1

Year 6 = 656.1 - 10% = 656.1 = 65.61 = $590.49

Hope this is clear enough

Cheers

To write a fraction on a computer, use the / sign.

So you would then write a fraction like 3/4, where the first number is the numerator and the second is the denominator.

Treat this like a long division problem, and let each term (like 3x^3) be like a number in a normal long division problem. Here's how'd you'd solve it:

I added 0x^2. This is really just a placeholder, or in other words, it doesn't need to be there. I just put it there to show you how it all lines up.

Here's a starter for a mathematics sub-category list

Arithmetic

Geometry

Trigonometry

Algebra

Calculus

Differential equations

Logic

Probability and statistics

I wonder if this is asking about how to express the position and velocity in terms of the unit vectors, i, j and k.

If so, then, using p for position and v for velocity:

p = sin(t)i + (t+1)j + cos(t)k

v = cos(t)i + j - sin(t)k

$${\frac{{\mathtt{x}}}{{\mathtt{8}}}} = {\mathtt{2}}$$

$${\frac{{\mathtt{x}}}{{\mathtt{8}}}}{\mathtt{\,\times\,}}{\mathtt{8}} = {\mathtt{2}}{\mathtt{\,\times\,}}{\mathtt{8}}$$

Now we solve this formula easily

x =16

This is the answer to this "x" variable

$${\frac{{\mathtt{x}}}{{\mathtt{8}}}} = {\mathtt{2}}$$

$${\mathtt{x}} = {\mathtt{2}}{\mathtt{\,\times\,}}{\mathtt{8}}$$

$${\mathtt{x}} = {\mathtt{16}}$$

Our answers are correct, ND....

The calculator confirms it......

5(6 / 22 * 3 - 1)

$${\mathtt{5}}{\mathtt{\,\times\,}}\left({\frac{{\mathtt{6}}}{{\mathtt{22}}}}{\mathtt{\,\times\,}}{\mathtt{3}}{\mathtt{\,-\,}}{\mathtt{1}}\right) = {\mathtt{\,-\,}}{\frac{{\mathtt{10}}}{{\mathtt{11}}}} = -{\mathtt{0.909\: \!090\: \!909\: \!090\: \!909\: \!1}}$$

And besides, two great minds like ours can never be mistaken............LOL!!!!

No problem. That one was a little tricky.

We got some different answers here so I'll solve it myself and hopefully we'll get a two of the same answer.

5[6 ÷ 22 · 3 - 1]            ---Write this as a fraction

5[6/22 · 3 - 1]              ---Simplify the fraction

5[3/11 · 3 - 1]               ---Multiply 3/11 times 3

5[9/11 - 1]                     ---Rewrite as two fractions

5[9/11- 11/11]              ---Subtract

5[-2/11]                    ---Multiply out

-10/11

CPhill and I both got this answers, so it should be right.

Hit the "2nd" button on the on-site calculator.....you will see the "acos" button....this  is the same as cos^-1 ..... (i.e., the cosine inverse)

5[6 ÷ 22 · 3 - 1]    Remember that we perform any multiplications/divisions as we encounter them from left to right....so.....working inside the brackets first, we have

5[ (6/22)*(3) -1] =

5[(18/22) - 1] =

5[9/11 - 1] =

5[9/11 - 11/11] =

5 [-2/11] =

-10/11

Correction:

5[6 ÷ 22 · 3 - 1]

=5[2 ÷ 22 - 1]

=5[1/11 - 1]

=5/11 - 5

=-50/11

4 · 1 - 32 ÷ 3  =

( 4 * 1 ) - ( 32 / 3) =

4 - (32 / 3) =

12/3 - 32/3 =

-20/3   or  -(6 + 2/3)

5[6 ÷ 22 · 3 - 1]

=5[6 ÷ 66 - 1]

=5[11 - 1]

=5 · 10

=50

(6 + 7/8) - (2 + 1/2) =

(55/8) - (5/2) =

(55/8) - (20/8) =

(35/8) =

4 + 3/8 cups

Well done, rosala....!!!!

However......we HAVE to ask the question before "awarding" you the "Crown".........did you "accidentally" stumble upon the answer here???.......

A three space unit vector is defined as <v₁ / llvll , v₂ / llvll , v₃ / llvll >  where v1, v2, v3 are the individual components  of a given vector, v, and llvll is the length of that vector.

So we have 

v = <sin(t) , t + 1 , cos(t) >      And llvll = √ (sin(t)² + (t + 1)² + (cos(t)² ) = √( t2 + 2t + 2)

So, our unit vector is  < sin(t) /  √( t2 + 2t + 2), (t + 1) / √( t2 + 2t + 2), cos(t) / √( t2 + 2t + 2) >

The same procedure could be used to find the length of the derivative vector.