Which term of gp 18,-12,8....is512/729
CBSE, JEE, NEET, CUET
Question Bank, Mock Tests, Exam Papers
NCERT Solutions, Sample Papers, Notes, Videos
Posted by Dab King 5 years, 4 months ago
- 1 answers
Test
Related Questions
Posted by Manoj Thakur 1 year, 4 months ago
- 0 answers
Posted by Sana Dharwad 1 year, 4 months ago
- 0 answers
Posted by Ashish Chaudhary 1 year, 4 months ago
- 1 answers
Posted by Gurleen Kaur 1 year, 4 months ago
- 0 answers
Posted by Sabin Sultana 1 year, 4 months ago
- 0 answers
Posted by Sethpoulou Apoulou 1 year, 5 months ago
- 0 answers
Posted by Ananya Sv 1 year, 4 months ago
- 1 answers
Posted by Nitin Kumar 1 year, 4 months ago
- 1 answers
myCBSEguide
Trusted by 1 Crore+ Students
Test Generator
Create papers online. It's FREE.
CUET Mock Tests
75,000+ questions to practice only on myCBSEguide app
Gaurav Seth 5 years, 4 months ago
Let the first term be 'a'
The common difference be 'r'
nth term is = a*r^(n-1)
So
first term
a1 = a*r^0
a = 18
second term
a2 = a*r^1 = -12
hence r = -2/3
Third term
a3 = 18*(-2/3)^2
= 8
Hence
a = 18
r = -2/3
512/729 = 18*(-2/3)^n -------(1)
after cross multiplying 18 we have to find the power of n which satisfies (-2/3)^n = 256/6561
we obtain (-2)^8 = 256 and 3^8 = 6561
therefore (1) becomes
18*(-2/3)^8 = 512/729
n-1 = 8
Therefore it is the 9th term
1Thank You