I did some questions from some trial papers and realised that some of my answers do not tally with the answer sheet. I have checked it numerous times and seem not to be able to spot any errors. Please take a look as I might have overlooked them.
Firstly, the binomial question.
Find the 1st 3 terms of the expansion, in ascending powers of x of (2x - 3)^5 and (1-3x)^5
I got -243 + 810x - 1080x^2 +... and 1 - 15x + 90x^2 +... respectively.
Next comes the part I did wrong.Hence, find the coefficient of x^2 in the expansion of (-6x^2 + 11x - 3)^5
The answer says it should be -13473 however I got a value LARGER than that... should you multiply (-243 + 810x - 1080x^2+...)(1-15x+90x^2+...)?
Second question.
given that the expression 2x^2 - 6x +5 leaves the same remainder when divided by x-p or x-q, where p is not equal to q, show that p+q = 3. Hence find the remainder when expression is divided by 2x - p -q.
I got 0.5 as the remainder but answer says it is -8.5. I'm pretty sure I got this answer correct cuz I checked it against the answer fro long division method. They tally.
Lastly, thanks all.
you are correct in both cases
and at this stage, you should be confident enough of your answers to know that the answer given is wrong, especially after you have verified with a 2nd method in Question 2.
Remember that this verification with a 2nd method is an excellent way to check your answers in exams; use it if you have the time when checking =D