Moderate -0.8 This is a straightforward application of standard summation formulae requiring expansion of (2r+3)² into 4r² + 12r + 9, then applying the formulae for Σr², Σr, and Σ1. While it involves algebraic manipulation and multiple steps, it's a routine textbook exercise with no problem-solving insight required, making it easier than average for Further Maths.
4 In this question you must show detailed reasoning.\\
Determine the value of $\sum _ { r = 1 } ^ { 100 } ( 2 r + 3 ) ^ { 2 }$.
\hfill \mbox{\textit{OCR Further Pure Core 2 2021 Q4 [3]}}