1.3 Geometric sequences and seriesIB Maths: Applications and Interpretation HL: Flashcards

What these 13 flashcards ask

Formula for the nth term of a geometric sequence?
Formula for Sn of a geometric series?
How do you find r from u2 and u5?
What is r for an increase of 4% per year?
What is r for a decrease of 8% per year?
What does \sum{k=1}^{n}uk mean?
Why is the power n-1 in u1r^{n-1}?
What must you write if you use a GDC for a sequence?
A sequence is 4,12,36,\ldots. Find u6.
If 0<r<1, what do the terms do?
How can you find the least n with un10\,000 on a GDC?
Which function type is a geometric sequence a model of?
Salary 36 000 AED rising 4% a year: salary in year 10?

Exam questions on 1.3 Geometric sequences and series

A geometric sequence has first term $u_1=4$ and common ratio $r=3$ .
Find the least value of $n$ for which $u_n>10\,000$ .2 marks
A virus spreads so that the number of new cases each day is 1.5 times the number of new cases on the day before. On day 1 there are 40 new cases.
Find the first day on which the number of new cases is greater than 1000.2 marks
A geometric sequence has $u_2=12$ and $u_5=96$ .
Find the common ratio $r$ and the first term $u_1$ .3 marks

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).