The matrices A, B and C are given by A = (1 2 3) (2 1 3) (3 2 5) B = (0 -2) (-1 3) (0 0) C = (-2 -1 1) (1 1 3)
- (a)Show that CAB = (3 -7) (-9 3)[3]
- (b)Find the equations of the invariant lines, through the origin, of the transformation in the x-y plane represented by CAB.[5]
- (c)Give full details of the transformation represented by M = (3 0) (0 1).[2]
- (d)Find the matrix N such that NM = CAB.[3]
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2024). The mark or mark type is shown in brackets.
- [M1 A1] Multiplying two matrices correctly, correct dimensions.
- [B1] Convincingly completing matrix multiplication, AG.
- [B1] Transforms (x, y) to (3x-7y, -9x+3y)
- [M1 A1] Uses y=mx and Y=mX.
- [A1]
- [A1]
- [B1] Stretch
- [B1] parallel to the x-axis, scale factor 3.
- [B1] M⁻¹ = (1/3 0)\n (0 1)
- [M1] Correct order
- [A1]
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