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I've given you a few points just to get you started. 

and thx

your welcome

Shelley's score = 90x

Terrence's score = 90x-20

Difference between them is (90x - 20 - 90x) = -20

So the constant term represents the difference between Shelly's and Terrence's scores.

Thanks for the thumbs up!

I see that you are new Needhelp.  Welcome to the web2.0calc forum.  I hope that you learn a lot and enjoy yourself here.

Melody.

Let the number be x

x+14

9(x+14)=225

x+14=225/9

x+14=25

x=11

White out? You mean the paint used to correct mistakes?

I thought correcting mistakes was my job? I am really good at it! 

The Professional Troll

Yes I have the white out ready so does CPhill!

Thanks Alan,

okay I did the 2P bit (before I deleted it) but I was confused because the ln2 was written in the question.

But what you have said makes sense.  I'll go back and finish it.

m(t) = 15e ^−0.071t

$$\begin{array}{rll}
m(t)&=&15e^{-0.071t}\\\\
1&=&15e^{-0.071t}\\\\
\frac{1}{15}&=&e^{-0.071t}\\\\
ln^{\frac{1}{15}}&=&ln{e^{-0.071t}}\\\\
ln^{\frac{1}{15}}&=&-0.071t\\\\
\frac{ln^{\frac{1}{15}}}{-0.071}&=&t\\\\
t&=&\frac{ln^{\frac{1}{15}}}{-0.071}\\\\


\end{array}$$

$${\frac{{ln}{\left({\frac{{\mathtt{1}}}{{\mathtt{15}}}}\right)}}{-{\mathtt{0.071}}}} = {\mathtt{38.141\: \!552\: \!128\: \!200\: \!140\: \!8}}$$

So in 38 days there will be just over 1g left.

In 39 days there will be less than 39 grams left.

Melody, if you put A = 2P (investment doubled) then take logs you get ln(2) = r*t or t = ln(2)/r.

The calculator on the Home page gives something slightly different:

It interprets the first part (up to and including the 2) as computerese for 1.0*10^-2 and then gets stuck because it expects an operator before the decimal point!

I'll just do the first one for you.

$$\\g(x) = log_3( x^2-9)\\\\
x^2-9>0\qquad \qquad \mbox{because you can only find the log of a positive number}\\\\
x^2>9\\\\
x<-3 \:\:or\:\: x>3$$

Check with a graph.

I am just going to do the first one for you.    (Completed after Alan's comment below)

1)   e ^x = 3

$$\\log_e3=x\\\\
x=ln3$$

Dpo the others the same way.

That is true Alan but what I was experimenting with is how this web2.0calc would interpret 

10000e-2.835

So I plugged it in and this is what I got.  So the web2 calc does not interpret it this way.

$$\mathrm{ERROR}$$

Thats pretty simple!Just have to write one single small step see:

$$7(c-2)$$

$$=7c-14$$  $$ANSWER$$

I jope uve understood by now but if not then pls be free to ask!

i hope this helps!

By using Google translator!Simple!

Melody i too could see it but i could do nothing becoz anonymous has written it like this!

BTW Your Welcome!

Melody i too googled it but i was getting different answers,maybe becoz i just wrote rm!

but thanks for telling!

Your Welcome Melody!

Your question needs brackets to make it unambiguous.

Is this is what you have asked.

$$15x^{1/2}y^{1/12}/(24x^{5/6}y^{1/6})\\\\
=\frac{15}{24}x^{1/2-5/6}y^{1/12-1/6}\\\\
=\frac{5}{8}x^{3/6-5/6}y^{1/12-2/12}\\\\
=\frac{5}{8}x^{-2/6}y^{-1/12}\\\\
=\frac{5}{8y^{1/3}y^{1/12}}$$

A number like 9.0e9 may be interpreted as 9.0*10⁹ only when the value following the "e" is an integer (positive or negative) and there is no exponentiation symbol ("^") between it and the "e".  In the question here, these conditions don't hold so we have to interpret this as:

$${\mathtt{10\,000}}{\mathtt{\,\times\,}}{{\mathtt{e}}}^{-{\mathtt{2.835}}} = {\mathtt{587.185\: \!258\: \!338\: \!722\: \!9}}$$ 

No.  Everything on the right-hand side would have to be over the same denominator before you could flip it.

So, here, for example you could collect everything on the RHS over 42.3*10²,

1/x = (9.4+4.5)/(42.3*10²) 

1/x = 13.9/(42.3*10²)  Now you can invert:

x = 42.3*10²/13.9  ≈ 304.32

Thanks Chris, I will have  to have a play.