Multiplying two matrices correctly, correct dimensions.
(3−7−93)
M1 A1
Completing matrix multiplication, AG.
5
Question (b)
(b)
Find the equations of the invariant lines, through the origin, of the transformation in the x-y plane represented by CAB.
[ 5 ]
(3−7−93)(yx)=(−9x+3y3x−7y)
B1
Transforms (yx) to (YX).
-9 x+3 m x=m(3 x-7 m x)
M1 A1
Uses y=m x and Y=m X.
−9+3m=3m−7m2⇒7m2=9
A1
y=73x and y=−73x
A1
5
Question (c)
(c)
The matrices D, E and F represent geometrical transformations in the x-y plane. - D represents an enlargement, centre the origin. - E represents a stretch parallel to the x-axis. - F represents a reflection in the line y=x.
Given that C A B=D-9 E F, find D, E and F.
[ 5 ]
D=(α0α)
B1
E=(β01)
B1
F=(010)
B1
(3−7−93)=(α0α)−9(0β10)
M1
Setting up simultaneous equations using their D and E.
D=(303)E=(9701)
A1
Condone α=3,β=97 if it is clear that they refer to the correct matrices.