Answers>Maths>IB>Article

The fifth term of an arithmetic sequence is equal to 6 and the sum of the first 12 terms is 45. Find the first term and the common difference.

Arithmatic term n, Un= U1+(n-1)d. Where U1 is the first term of the sequence and d is the common difference. U5=U1+4d=6. U1=6-4d. Sum of arithmatic terms up to term n, Sn=n/2(2U1+(n-1)d). S12=12/2(2(6-4d)+(12-1)d)=45. 6(12-8d+11d)=45. 12+3d=45/6. 3d=7,5-12=-4,5. d=-4.5/3=-1,5. U1=6-4*(-1,5)=6+6=12

JS
Answered by Jasmin S. Maths tutor

8645 Views

See similar Maths IB tutors

Related Maths IB answers

All answers ▸

f(x)=sin(2x) for 0<x<pi, find the values of x for which f is a decreasing function


a) Let u=(2,3,-1) and w=(3,-1,p). Given that u is perpendicular to w, find the value of p. b)Let v=(1,q,5). Given that modulus v = sqrt(42), find the possible values of q.


Given the parametric equations x = lnt+t and y = sint calculate d^2y/dx^2


How does the right angle triangle definition of sine, cosine and tangent relate to their graphs as a function of angle and to Euler's formula?


We're here to help

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

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences