Question 4 - A-Level Maths

Exam Board	AQA
Module	Further Paper 2 (Further Paper 2)
Year	2021
Session	June
Marks	3
Topic	Arithmetic Sequences and Series

Show that $$( r + 1 ) ^ { 2 } - r ^ { 2 } = 2 r + 1$$ 4
Use the method of differences to show that $$\sum _ { r = 1 } ^ { n } ( 2 r + 1 ) = n ^ { 2 } + 2 n$$ 4
Verify that using the formula for $\sum _ { r = 1 } ^ { n } r$ gives the same result as that given in part (b).
[0pt] [3 marks]