Further Pure Mathematics 4PM1 / Sequences and Series / 1.81.8: Evaluate sums using sigma notation4PM1/2/November/2020 — Question 5 · 8 marksMark as done · Save for later(a) Show that∑r=1n(3r+5)=12n(3n+13).\sum_{r=1}^{n}(3r+5)=\frac12n(3n+13).r=1∑n(3r+5)=21n(3n+13).(3)(b) Hence evaluate∑r=3550(3r+5).\sum_{r=35}^{50}(3r+5).r=35∑50(3r+5).(2)Given that∑r=1n(3r+5)=385,\sum_{r=1}^{n}(3r+5)=385,r=1∑n(3r+5)=385,(c) find the value of n\displaystyle nn.(3)▸ Mark scheme← 1.7: 4PM1/1R/November/2020 — Question 31.9: 4PM1/2/November/2020 — Question 7 →
