Telescoping product from a conjugate factorisation

Telescoping product from a conjugate factorisation

Secondary 2
4 marks
TGM Original Questions

Optional extension

Factorise \(1-\dfrac1{n^2}\), where \(n\ne0\). Hence evaluate \(\left(1-\dfrac1{9^2}\right)\left(1-\dfrac1{10^2}\right)\cdots\left(1-\dfrac1{15^2}\right)\).[4]

Solution:

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Answer:(a) \(\frac{(n-1)(n+1)}{n^2}\) (b) \(\frac{128}{135}\).

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