Date | May Example question | Marks available | 3 | Reference code | EXM.2.AHL.TZ0.22 |
Level | Additional Higher Level | Paper | Paper 2 | Time zone | Time zone 0 |
Command term | Show that | Question number | 22 | Adapted from | N/A |
Question
Let M2 = M where M = .
Show that .
Find an expression for in terms of .
Hence show that M is a singular matrix.
If all of the elements of M are positive, find the range of possible values for .
Show that (I − M)2 = I − M where I is the identity matrix.
Markscheme
Attempting to find M2 M1
M2 = A1
or A1
Hence (as or ) AG N0
[3 marks]
M1
A1 N1
[2 marks]
METHOD 1
Using det M = M1
det M = or det M =
(or equivalent) A1
using or to simplify their expression R1
Hence M is a singular matrix AG N0
METHOD 2
Using and to obtain M1A1
det M = and as R1
Hence M is a singular matrix AG N0
[3 marks]
(M1)
0 < < 1 A1A1 N3
Note: Award A1 for correct endpoints and A1 for correct inequality signs.
[3 marks]
METHOD 1
Attempting to expand (I − M)2 M1
(I − M)2 = I − 2M + M2 A1
= I − 2M + M A1
= I − M AG N0
METHOD 2
Attempting to expand (I − M)2 = (or equivalent) M1
(I − M)2 =
(or equivalent) A1
Use of and to show desired result. M1
Hence (I − M)2 = AG N0
[3 marks]