Solve the inequality |2x – 7| < |2x – 9|.
- (i)Solve the inequality |2x – 7| < |2x – 9|.[3]
- (ii)Hence find the largest integer n satisfying the inequality |2 ln n – 7| < |2 ln n − 9|.[2]
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2019). The mark or mark type is shown in brackets.
- [M1] State or imply non-modular inequality (2x−7)² < (2x−9)² or corresponding equation or linear equation (with signs of 2x different)
- [A1] Obtain critical value 4
- [A1] State x < 4 only
- [M1] Attempt to find n from Inn = their critical value from part (i)
- [A1] Obtain or imply n<e⁴ and hence 54
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