A-LevelMathematicsSeries9709/12 · Feb/Mar 2017 · Q24 Marks
In the expansion of (1/ax + 2ax²)⁵, the coefficient of x is 5. Find the value of the constant a.
- (a)In the expansion of (1/ax + 2ax²)⁵, the coefficient of x is 5. Find the value of the constant a.[4]
Mark scheme
Marking points from the official mark scheme (Feb/Mar 2017). The mark or mark type is shown in brackets.
- [B1] 5C2 (1/ax)² (2ax²)³ soi
- [M1A1] M1 for identifying relevant term and equating to 5, all correct. Ignore extra x 10x(1/a)²x 4a² = 5 soi
- [A1] a = 8 cao
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