An arithmetic series is given by
∑n=1150(bn+c)\sum_{n=11}^{50} (bn + c)∑n=1150(bn+c)
where b b\,b and c c\,c are constants. The sum of the series is 2680.
Show that 61b+2c=13461b + 2c = 13461b+2c=134.
Given that the 21st term of the sequence un=bn+cu_n = bn + cun=bn+c is 4 times its 3rd term, find the value of b b\,b and the value of ccc.
231 exam-style questions on WJEC A Level Maths 3.4 Sequences and Series (A-level only), covering 3.4.1 Sequences and Series (A-level only), 3.4.2 Sequences and Series (A-level only), 3.4.3 Sequences and Series (A-level only), 3.4.4 Sequences and Series (A-level only), 3.4.5 Sequences and Series (A-level only), 3.4.6 Sequences and Series (A-level only), and 3.4.7 Sequences and Series (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.