Melody

I don't understand this question

$$sinxcos30-cosxsin30=\frac{sinx-\sqrt3cosx}{2}$$

No there is no solutions to this.

how many years will it take to double $1000 at 20% interest.

$$\\2000=1000(1.2)^n\\
2=1.2^n\\
log2=log(1.2^n)\\
log2=nlog1.2\\
n=log2\div log 1.2$$

$${\frac{{log}_{10}\left({\mathtt{2}}\right)}{{log}_{10}\left({\mathtt{1.2}}\right)}} = {\mathtt{3.801\: \!784\: \!016\: \!923\: \!930\: \!7}}$$

almost 4 years.

18 r s to the 0'th power t to 9th power over.

6 r to the 8th s to seventh and t to the fourth.

$$\\\dfrac{18rs^0t^9 }{ 6r^8s^7t^4}\\\\

=\dfrac{3rt^9 }{ r^8s^7t^4}\\\\

=\dfrac{3t^{9-4} }{ r^{8-1}s^7}\\\\

=\dfrac{3t^{5} }{ r^{7}s^7}\\\\$$

Hi Natthada,

Can you use the [calculation] button and type this calculation straight onto the forum please so that we can see the 'working' please ? 

3 because  4^3=64

Remember, a log is a power .

Radians and degrees both measure angles. 

There are  2pi radians in a revolution and there are 360 degrees in a revolution.

Well, we constantly remind children not to give out their full names, addresses, schools, telephone numbers etc.  We advise them on how to deal with unpleasant messages and I am very available if they want to discuss any issues by private messages.  (As is CPhill if they prefer to approach him.)

So I think this site is as safe as any internet site can be.  And safer than most of them are.  

We have a few adult mathematicians working the site.  They are all wonderful prople.  We have many young members.  Again they overwealmingly lovely people.  This is a children's maths site.  It is as safe as it gets.

$${\frac{{\mathtt{5}}}{{\mathtt{7}}}} = {\mathtt{0.714\: \!285\: \!714\: \!285\: \!714\: \!3}}$$

I just entered  5/7