O-LevelAdditional MathematicsSimultaneous equations4037/12 · May/June 2013 · Q89 Marks
(a) Given that the matrix A = (4 2 \ 3 -5), find
- (a)(i)A²,[2]
- (a)(ii)3A + 4I, where I is the identity matrix.[2]
- (b)(i)Find the inverse matrix of (6 1 \ -9 3).[2]
- (b)(ii)Hence solve the equations 6x + y = 5, -9x + 3y = 3/2.[3]
Mark scheme
Marking points from the official mark scheme (May/June 2013). The mark or mark type is shown in brackets.
- [2] (22 -2 \ -3 31) B2, 1, 0 -1 each element error
- [2] (16 6 \ 9 -11) B2, 1, 0 -1 each element error
- [1] B1 for 1/determinant (allow unsimplified)
- [1] B1 for matrix
- [1] M1 for correct use of inverse matrix, including correct multiplication to solve equation
- [1] x = 0.5, y = 2 A1 for each
- [1] x = 0.5, y = 2 A1 for each
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