Class 11 Mathematics - Chapter Sequence and Series NCERT Solutions | Find the 12th term of a G.P. whose

Welcome to the NCERT Solutions for Class 11th Mathematics - Chapter Sequence and Series. This page offers a step-by-step solution to the specific question from Exercise 3, Question 2: find the 12th nbsp term of a g p whose 8th nbsp t....
Question 2

Find the 12th term of a G.P. whose 8th term is 192 and the common ratio is 2.

Answer

Common ratio, r = 2

Let a be the first term of the G.P.

∴ a8 = ar 8–1 = ar7

⇒ ar7 = 192

a(2)7 = 192

a(2)7 = (2)6 (3)

rightwards double arrow a equals fraction numerator open parentheses 2 close parentheses to the power of 6 cross times 3 space over denominator open parentheses 2 close parentheses to the power of 7 end fraction equals 3 over 2
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a subscript 12 space equals a r to the power of 12 minus 1 end exponent space equals space open parentheses 3 over 2 close parentheses open parentheses 2 close parentheses to the power of 11 equals open parentheses 3 close parentheses open parentheses 2 close parentheses to the power of 10 equals 3072

 

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