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

Answered by Jasmin S. Maths tutor

8372 Views

See similar Maths IB tutors

Related Maths IB answers

All answers ▸

Write down the expansion of (cosx + isinx)^3. Hence, by using De Moivre's theorem, find cos3x in terms of powers of cosx.


How do I integrate the volume of revolution between 0 and pi of y=sin(x)?


How does Euclid's algorithm give solutions to equations?


A sequence of numbers have the property that x, 12, y, where x > 0, y > 0, form a geometric sequence while 12, x, 3y form an arithmetic sequence. A)If xy = k, find k. B)Find the value of x and y.


We're here to help

contact us iconContact usWhatsapp logoMessage us on Whatsapptelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences