Edexcel Mathematics June 2019 · Paper 1 · Question 4 · ExamRizz

ExamRizzEdexcel MathematicsMathematics

June 2019 · Paper 1 · Question 4 · 6 marks

4. (a) Find the first three terms, in ascending powers of x, of the binomial expansion of 1 4−x giving each coefficient in its simplest form. (4) The expansion can be used to find an approximation to 2 Possible values of x that could be substituted into this expansion are: Ɣ x = –14 because 1 41 182 6 −== x Ɣ x = 2 because 1 41 22 2 −== x Ɣ x = −1 2 because 1 41 9 22 3 −== x (b) Without evaluating your expansion, (i) state, giving a reason, which of the three values of x should not be used (1) (ii) state, giving a reason, which of the three values of x would lead to the most accurate approximation to 2 (1)

Lesson: Binomial Expansion for Positive Integer n