No, with respect to x. You want to go from a general term of x^-r to a term of rx^-(r+1). To get the old power in front of the x you need to differentiate and multiply by -1 to remove the negative. See the 2002 specimen paper for a full solution.
Ohhhhhhhhhh so you differentiate section a's answer?! That makes some sense.
Ohhhhhhhhhh so you differentiate section a's answer?! That makes some sense.
Alternatively, call the sum S, and consider xS. Note that S - xS gives a geometric series which can be summed, and so S = that sum divided by (1-x). Personally I prefer this method as using calculus is like using a sledgehammer to crack a nut.
Alternatively, call the sum S, and consider xS. Note that S - xS gives a geometric series which can be summed, and so S = that sum divided by (1-x). Personally I prefer this method as using calculus is like using a sledgehammer to crack a nut.
Yes your approach works just as well. That method and the calculus method are the most common ways of dealing with arithmetico-geometric series such as these.
I didn't sit it but a first look at the PDF file suggests it was probably harder than 2015.
I agree, i sat 2015 n it was rather easy, this was harder imho aswell. I reckon 65 for distinction. I expected last years to be 75 for distinction but turnednout to be 70.
Alternatively, call the sum S, and consider xS. Note that S - xS gives a geometric series which can be summed, and so S = that sum divided by (1-x). Personally I prefer this method as using calculus is like using a sledgehammer to crack a nut.
Never come across either methord before unfortunately.
Never come across either methord before unfortunately.
HHere's you get that from.
If what you're asking is where I got the paper from, the answer is I downloaded it from Edexcel's Maths Emporium, since I was able to convince them I was a teacher.
I agree, i sat 2015 n it was rather easy, this was harder imho aswell. I reckon 65 for distinction. I expected last years to be 75 for distinction but turnednout to be 70.
That's interesting because I thought last years was harder. Here's my thoughts: Question 1: Thought this was fairly standard. Function questions seem to be popular with Edexcel and are usually answered pretty well, maybe with some slips being made on domain and range. Question 2: I think this would've been a non-starter for many, mainly due to the unusual nature of the question. Question 3: I think most people would've picked up a few marks here, even if finding OE was problematic. Question 4: I think a lot of able people will have scored near-full marks on this one. It wasn't too difficult. Question 5: Seems to have caused a few problems, especially parts (b) and (c), although similar questions have been asked before. People should've been able to pick up a few method marks, regardless. Question 6: Quite straightforward integration by substitution. Question 7: Part (a) was a little fiddly, the integer solutions may have caught a few out but the rest wasn't too difficult.
Think boundaries will be hard to call. If you look at some of the very early ones they were quite high (e.g. 2003), despite the papers being quite difficult. I think the distinction boundary for 2014 was 69, but I don't think this was more difficult than 2014.
If what you're asking is where I got the paper from, the answer is I downloaded it from Edexcel's Maths Emporium, since I was able to convince them I was a teacher.
If what you're asking is where I got the paper from, the answer is I downloaded it from Edexcel's Maths Emporium, since I was able to convince them I was a teacher.
Yeah I am. I can't help but wonder if that is legal...
Yeah I am. I can't help but wonder if that is legal...
To get an account and convince them you are a teacher, all you need is a centre email address, i.e. something ending in .sch.uk or .edu or .org.uk, rather than a private Gmail/Hotmail account. Since my school gives both students and teachers centre email addresses, it was easy.
To get an account and convince them you are a teacher, all you need is a centre email address, i.e. something ending in .sch.uk or .edu or .org.uk, rather than a private Gmail/Hotmail account. Since my school gives both students and teachers centre email addresses, it was easy.
If you're referring to the username and password I just gave, I checked it and it does work. Try copying and pasting the details, exactly as shown, into the login form on www.edexcelmaths.com
To get an account and convince them you are a teacher, all you need is a centre email address, i.e. something ending in .sch.uk or .edu or .org.uk, rather than a private Gmail/Hotmail account. Since my school gives both students and teachers centre email addresses, it was easy.