## Archive for the ‘2017 Maths’ Category

Wednesday, November 15th, 2017

Thanks to Gavin Rogers for pointing out a mistake in Q4f, the correct answer is b=-(a+4)+2Im(a) i

Thanks to Pablo Kucz for a simpler answer to Q4f, b = – 4 – conjugate of a

Saturday, November 11th, 2017

Thanks to Cameron Dole for pointing out the following mistakes. Quote: “MC17 is D not B. Option B has both methods of turning an area below graph to positive (placing neg in front and swapping limits) so they cancel out and give a negative value. Option D doubles the area from a to b (due to symmetry as f(x)=f(-x)) and then doubles area from b to 0 but uses b+c to get 0 as well as placing neg in front.
Q3f I agree with working but both CAS and a manual factorisation gives me 7p^2(p-1)^4(2p+3) which does nor expand to your answer. Then of course answers to both parts of 3g are incorrect as a consequence.”

Also thanks to Raymond Rozen of RMIT University and Linda Harland for pointing out the mistakes and providing feedback.

Saturday, November 11th, 2017

Thanks to Emma Mullane of McKinnon S.C. and Trang Pham for pointing out a mistake in Q6, arcsin(x) should be squared.

Wednesday, November 8th, 2017

Wednesday, November 8th, 2017

Thanks to Frank Ngari for pointing out four mistakes in the solutions.
Matrices Q3a should be ( 0.4 0.4 0.2 0.2) times column matrix ( 300 200 200 3000) and the answer is 320.
Geometry and measurement Q2a should be Tokyo is 2 hours behind hence the time is 8.00 pm on Wednesday.
Q2c radius should be 6400cos 43 = 4681km.
Q3b should be length of major arc hence the perimeter is 438 and not 266.

Monday, November 6th, 2017

Thanks to Lyn Harris for checking the solutions and providing feedback. Lyn has been supporting us for many years. We greatly appreciate her professional contributions.

Sunday, November 5th, 2017

Thanks to Bill Yuan and Kelvin Rogash for pointing out that B is the correct answer to both Q8 and Q22.

Friday, November 3rd, 2017

Thanks to Lyn Harris for checking the solutions and providing valuable feedback.