You are Here: Home >< Maths

1. Okay, there off the C3 Specimen paper (link below)

http://www.edexcel.org.uk/VirtualCon...r_MkScheme.pdf

Q4a. I have got to the stage of: (x³+2x²-3)/ (x+3)(x-1) but cant see what they've done to get to the next step.

Q5c. i've put y=0 to get e^0 = (2x+3)^3

Hence: ³√1 = ³√(2x+3)

so: ±1 = 2x+3

Why have they taken the +ve root of 1 and not the -ve?

Thanks
2. Q4a. You divide x³+2x²-3 by (x-1) by algebraic division to give (x²+3x+3)(x-1)/(x+3)(x-1)... The (x-1)'s then cancel et voila!
3. Q5c. I did it this way:

y=0, so 3ln(2x+3) = 0 then divide both sides by 3 to give ln(2x+3) = 0
then 2x+3 = e^0 so 2x+3 = 1 so x = -1 therefore p = -1
4. Why have they taken the +ve root of 1 and not the -ve?
you don't get any negative roots from cube rooting i.e the cube root of 1 is 1
5. (Original post by !Laxy!)
Q5c. i've put y=0 to get e^0 = (2x+3)^3

Hence: ³√1 = ³√(2x+3)

so: ±1 = 2x+3

Why have they taken the +ve root of 1 and not the -ve?

Thanks
after you put y = 0, you got

e^0 = (2x+3)^3
or
1 = (2x+3)^3

.: (2x+3) must be +ve, since if it was -ve, then so also would be its cube!

So, express (2x+3) as the (+ve) cube root of 1.

Another reason is that you can't get a -ve (cube) root of 1!!
6. (Original post by violet)
Q4a. You divide x³+2x²-3 by (x-1) by algebraic division to give (x²+3x+3)(x-1)/(x+3)(x-1)... The (x-1)'s then cancel et voila!

Why do you divide by (x-1)???
7. Because otherwise you wouldn't know what the other factor of x³+2x²-3 was, so you wouldnt know what was left once you'd cancelled the (x-1)s.

Related university courses

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: June 12, 2005
The home of Results and Clearing

3,163

people online now

1,567,000

students helped last year
Today on TSR

University open days

1. Sheffield Hallam University
Tue, 21 Aug '18
2. Bournemouth University
Wed, 22 Aug '18
3. University of Buckingham
Thu, 23 Aug '18
Poll
Useful resources

Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

How to use LaTex

Writing equations the easy way

Study habits of A* students

Top tips from students who have already aced their exams

Chat with other maths applicants