A start-up company tracks its daily net cash flow, CnC_nCn, in pounds (£\pounds£). The cash flow follows an arithmetic sequence with first term aaa and common difference ddd.
The total net cash flow over the first 12 days is £\pounds£ 432.
Show that 4a+22d=1444a + 22d = 1444a+22d=144.
Given that the total net cash flow over the first 30 days is £\pounds£ 0, determine the total net cash flow over the first 15 days.
SnS_nSn represents the sum of the daily net cash flow for the first nnn days. Explain why the value you calculated in part (b) is the maximum value of SnS_nSn.
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.