Date | May Example question | Marks available | 2 | Reference code | EXM.2.AHL.TZ0.8 |
Level | Additional Higher Level | Paper | Paper 2 | Time zone | Time zone 0 |
Command term | Write down | Question number | 8 | Adapted from | N/A |
Question
The function ff is given by f(x)=mx3+nx2+px+qf(x)=mx3+nx2+px+q, where mm, nn, pp, qq are integers.
The graph of ff passes through the point (0, 0).
The graph of ff also passes through the point (3, 18).
The graph of ff also passes through the points (1, 0) and (–1, –10).
Write down the value of qq.
Show that 27m+9n+3p=1827m+9n+3p=18.
Write down the other two linear equations in mm, nn and pp.
Write down these three equations as a matrix equation.
Solve this matrix equation.
The function ff can also be written f(x)=x(x−1)(rx−s)f(x)=x(x−1)(rx−s) where rr and ss are integers. Find rr and ss.
Markscheme
* This question is from an exam for a previous syllabus, and may contain minor differences in marking or structure.
qq = 0 A1 N1
[1 mark]
Attempting to substitute (3, 18) (M1)
m33+n32+p3=18m33+n32+p3=18 A1
27m+9n+3p=1827m+9n+3p=18 AG N0
[2 marks]
mm + nn + pp = 0 A1 N1
−mm + nn − pp = −10 A1 N1
[2 marks]
Evidence of attempting to set up a matrix equation (M1)
Correct matrix equation representing the given equations A2 N3
eg (2793111−11−1)(mnp)=(180−10)⎛⎜⎝2793111−11−1⎞⎟⎠⎛⎜⎝mnp⎞⎟⎠=⎛⎜⎝180−10⎞⎟⎠
[3 marks]
(2−53)⎛⎜⎝2−53⎞⎟⎠ A1A1A1 N3
[3 marks]
Factorizing (M1)
eg f(x)=x(2x2−5x+3)f(x)=x(2x2−5x+3), f(x)=(x2−x)(rx−s)f(x)=(x2−x)(rx−s)
r=2r=2 s=3s=3 (accept f(x)=x(x−1)(2x−3)f(x)=x(x−1)(2x−3)) A1A1 N3
[3 marks]