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2019 WAEC Further Mathematics Theory Given that (\(_r^n\)) = \(^nC_r\), simplify (\(^{2x + 1}_{3}\)) - (\(^{2x - 1}_3\)) - 2(\(^x_2\))

Further Mathematics
WAEC 2019

Given that (\(_r^n\)) = \(^nC_r\), simplify (\(^{2x + 1}_{3}\)) - (\(^{2x - 1}_3\)) - 2(\(^x_2\))

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Explanation

(\(^{2x + 1}_{3}\)) = \(\frac{(2x + 1)!}{3!(2x - 2)!} = \frac{(2x + 1)2x(2x - 1)}{6}\)

(2x - 1) = \(\frac{(2x - 1)!}{3!(2x - 4)!} = \frac{(2x - 1)(2x -2)(2x - 3)}{6}\) and 2(\(^x_2\)) = 2 [\(\frac{x!}{2!(x - 2)!}\)] 

2[\(\frac{x(x - 1)}{2}\)] = x(x - 1)

Substitute; (\(^{2x + 1}_3\)) - (\(^{2x + 1}_3\)) - 2(\(^x_2\)) 

\(\frac{(2x + 1) 2x(2x - 1)}{6} - \frac{(2x - 1)(2x - 2)(2x - 3)}{6} - x(x - 1)\)

Multiplying through by 6 and simplifying to arrive at; 3\(x^2 - 3x + 1\) 


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WAEC Past Questions, Objective & Theory, Study 100% offline, Download app now - 24709
WAEC May/June 2024 - Practice for Objective & Theory - From 1988 till date, download app now - 99995
Post-UTME Past Questions - Original materials are available here - Download PDF for your school of choice + 1 year SMS alerts
WAEC offline past questions - with all answers and explanations in one app - Download for free
WAEC May/June 2024 - Practice for Objective & Theory - From 1988 till date, download app now - 99995
WAEC Past Questions, Objective & Theory, Study 100% offline, Download app now - 24709
Post-UTME Past Questions - Original materials are available here - Download PDF for your school of choice + 1 year SMS alerts
WAEC offline past questions - with all answers and explanations in one app - Download for free