The second and fifth terms of a geometric series are 750 and -6 respectively. Find: (1) the common ratio; (2) the first term of the series; (3) the sum to infinity of the series

xn = ar(n-1)(1) x2 = 750 = ar1(2) x5 = -6 = ar4divide second equation by first-6/750 = r3r3 = -0.008r= -0.2Insert into first equation.750 = a * -0.2a = -3750Sum to infinite series = a(1/(1-r))(insert known variables)Sum to infinite series = -3750 * 1/1.2= -3125

HP
Answered by Henry P. Maths tutor

6167 Views

See similar Maths A Level tutors

Related Maths A Level answers

All answers ▸

Integrate sin(x)cos(x)^2 from 0 to π/2


The rate of growth of a population of micro-organisms is modelled by the equation: dP/dt = 3t^2+6t, where P is the population size at time t hours. Given that P=100 at t=1, find P in terms of t.


What is a stable solution and what is dominance?


Find the first and second derivative of f(x) = 6/x^2 + 2x


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

MyTutor is part of the IXL family of brands:

© 2026 by IXL Learning