Edexcel Mathematics Sample paper · Paper 2 · Question 7 · ExamRizz

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Sample paper · Paper 2 · Question 7 · 5 marks

7. (a) Use the binomial expansion, in ascending powers of x, to show that 4 2 1 − = − + + x x kx 2 ( )... 4 where k is a rational constant to be found. (4) A student attempts to substitute x = 1 into both sides of this equation to find an approximate value for 3 . (b) State, giving a reason, if the expansion is valid for this value of x.

Lesson: Binomial Expansion for Positive Integer n