Melody

What do you have against unicorns?

@@ End of Day Wrap - Monday 2/6/14   Sydney, Australia   Time 10:45 pm 

Hi Everyone,

Our great answers today were provided by CPhill, Alan, GoldenLeaf, admin, Stu, reinout-g, TaviSage, Kitty,3, Itoen, Feitan and Bertie.  Thank you all.

Feitan and TaviSage are both new.  We welcome you to web2.0calc forum and we hope you like it here.

Oh, Admin has introduced an avatar feature.  A number of members have told me that they love it. Thank you Andre.  Your efforts, and the improvements that they bring, are much appreciated.  

I have checked all posts up to but not including the current pages. (there is at least one that i want to return to tonight) 

Here are a couple of the more memorable threads.  

Great probability question - and comedy for the day!  

The chain rule is very basic and I do not think that it is expained to students very well.

Do you know how you can cancel in fractions

eg

speed*time = distance

because

$$\frac{6km}{hour}\times\frac{7hour}{1}=42km$$  Because the hours cancel out!

With calulus the d in front of the x and the y etc just stands for difference.  You can cancel out the units just like I did in the above example.

So for instance

$$\frac{dy}{du}\times \frac{du}{dx}\times \frac{dx}{dt}=\frac{dy}{dt}$$     The du's and dx's cancel out.

That is the chain rule!

Yes Stu, if two lines are perpendicular then the product of their gradients will be -1

$$m_1m_2=-1\\\\
therefore\\\\
m_2=\dfrac{-1}{m_1}$$

The normal to a curve is the name given to a line that is perpendicular to the tangent of the curve at that point.

That is;  The normal is perpendicular to the tangent.

WOW I could play Sibelius's Violin Concerto when I was 4.  I must have been a slow learner!

A positive number is always greater than a negative number so it must be true.

What is the : sign doing in there?  I do not understand the question!

Thanks Kitty

YES the question asker had it right in the first place!

That is not nice Kalecia!  If you can't say something nice don't say anything at all!