Edexcel C34 2018 October — Question 6

Exam BoardEdexcel
ModuleC34 (Core Mathematics 3 & 4)
Year2018
SessionOctober
TopicGeneralised Binomial Theorem
TypeDirect quotient expansion

6. (a) Use binomial expansions to show that, for \(| x | < \frac { 1 } { 2 }\)
(b) Find the exact value of \(\sqrt { \frac { 1 + 2 x } { 1 - x } }\) when \(x = \frac { 1 } { 10 }\) Give your answer in the form \(k \sqrt { 3 }\), where \(k\) is a constant to be determined.
(c) Substitute \(x = \frac { 1 } { 10 }\) into the expansion given in part (a) and hence find an approximate value for \(\sqrt { 3 }\) Give your answer in the form \(\frac { a } { b }\) where \(a\) and \(b\) are integers. $$\sqrt { \frac { 1 + 2 x } { 1 - x } } \approx 1 + \frac { 3 } { 2 } x + \frac { 3 } { 8 } x ^ { 2 }$$