Matrices A and B are such that A = ( (3a, 2b), (-a, b) ) and B = ( (-a, b), (2a, 2b) ) where a and b are non-zero constants.
- (i)Find A⁻¹.[2]
- (ii)Using your answer to part (i), find the matrix X such that XA = B.[4]
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2014). The mark or mark type is shown in brackets.
- [2] B1 for 1/(5ab), B1 for ( (b, -2b), (a, 3a) )
- [1] M1 for post-multiplication by inverse matrix X = BA⁻¹
- [1] DM1 for correct attempt at matrix multiplication, needs at least one term correct for their BA⁻¹ (allow unsimplified)
- [2] A1 A1 for each correct pair of elements, must be simplified ( (0, 1), (4, 2), (5, 5) )
Write your answer and get it marked
On Oracle Prep you can write or photograph your own answer and have it marked by AI against this mark scheme, with feedback on what you missed.
Sign up free →