Date | May Specimen paper | Marks available | 5 | Reference code | SPM.2.AHL.TZ0.9 |
Level | Additional Higher Level | Paper | Paper 2 | Time zone | Time zone 0 |
Command term | Find | Question number | 9 | Adapted from | N/A |
Question
Consider the graphs of y=x2x−3 and y=m(x+3), m∈R.
Find the set of values for m such that the two graphs have no intersection points.
Markscheme
METHOD 1
sketching the graph of y=x2x−3 (y=x+3+9x−3) M1
the (oblique) asymptote has a gradient equal to 1
and so the maximum value of m is 1 R1
consideration of a straight line steeper than the horizontal line joining (−3, 0) and (0, 0) M1
so m > 0 R1
hence 0 < m ≤ 1 A1
METHOD 2
attempting to eliminate y to form a quadratic equation in x M1
x2=m(x2−9)
⇒(m−1)x2−9m=0 A1
EITHER
attempting to solve −4(m−1)(−9m)<0 for m M1
OR
attempting to solve x2 < 0 ie 9mm−1<0(m≠1) for m M1
THEN
⇒0<m<1 A1
a valid reason to explain why m=1 gives no solutions eg if m=1,
(m−1)x2−9m=0⇒−9=0 and so 0 < m ≤ 1 R1
[5 marks]