Need help with HSC question (1 Viewer)

[BlueGas]

I need help with ii) how does (P-2r)/r get you r^2?

 

[InteGrand]

I need help with ii) how does (P-2r)/r get you r^2?

Now just expand out the brackets.

 

[BlueGas]

Now just expand out the brackets.

If you expand the brackets, you'll get Pr - 2r^2?

 

[InteGrand]

If you expand the brackets, you'll get Pr - 2r^2?

 

[Flop21]

You have to multiply everything by 0.5r^2. Once you do that, you'll see you can factorise the "r" and then you can cancel it top from bottom, then you get your answer.



Also I tried to make it nice and easy to see by using LaTeX, but it's too hard and stuffed up. Sorry.

 

[BlueGas]

But if 1/2 is used to get r^2 then why is there still a 1/2 in the equation if it was already used to half 2?

 

[Flop21]

That's how you do it. Let me know what line you don't understand.

 

[BlueGas]

That's how you do it. Let me know what line you don't understand.

Ah that's what I didn't understand. I didn't realise there was another 1/2 multiplied to PR, I thought after 1/2 was multiplied to 2 there would be no 1/2 left, thanks!

 

[InteGrand]

Ah that's what I didn't understand. I didn't realise there was another 1/2 multiplied to PR, I thought after 1/2 was multiplied to 2 there would be no 1/2 left, thanks!