Melody

I have asked you politely to stop dragging these old posts up.  Do you get the idea now!

This is very old garbage that you have dragged back up and i do not a appreciate you doing so!

PLEASE ADD A TITLE TO YOU QUESTION!

You have just found the area of the middle bit

( 10-2x )^2 

You would have to add 4 lots of  x(10-2x)  to make your answer correct.

Look at my diagram and see if you can see this.  

You are short a bracket.

What is between the 6 and the 3?

When you work out the answers to these you can just put it onto the calculator on the home page. 

Because you had a square peice of paper 10cm * 10cm.  That was 100cm^2

then you cut a square out of each of the 4 corners that was [xcm * xcm]*4 = 4x^2 cm^2

so you were left with  [100-4x²] cm²  of paper   

You need to give this question a title please.

This is interesting Alan,

You use calculus in a way that I have not seen it used before (or I don't remember anyway)

I have just enough of knowlege to attempt to understand

2x^2 -2x +5

tangent function : 4x-2

Average = sum of all tangents(numerator makes sense) over number of tangents (okay I am having trouble with the denominator)

Maybe I just need to think it through.  Can you help me get my mind around it?   

$$\\It\; is\; 100-4x^2\\\\
\mbox {But this is not one of the answers so we need to look some more}\\
100=10^2\\
4x^2=(2x)^2\\
\mbox{So we have a difference of two squares}\\
100-4x^2=(10-2x)(10+2x)\\
\mbox{So the answer is c}\\$$

I have heard this term before 'decimal fraction' but it does not really make sense.

Maybe you would like to explain what they are?

The meaning of your question is not clear.

What percentage is 15 of 200:  7.5%

What is 15% of 200:  15/100*200=30

Thanks 15x3

Flattery and thumbs up will get you a very long way with me.  

DS, 

15x3 expressely asked for this to be solved WITHOUT a calculator.  So, did you really answer the question?

This is a rhetorical question - don't dare post an answer!