Q. 33
The sums of n terms of two arithmetic progressions are in the ratio 5n + 4: 9n + 6. Find the ratio of their 18th terms
Answer :
assuming first AP whose first term is a and common difference d
To find: the ratio of 18th term of a given AP
we know that the sum of AP is given by the formula:
Substituting the values in the above equation
assuming second AP whose first term is A and common difference D
we know that the sum of AP is given by the formula:
substituting the values in the above equation
…. (i)
Given the ratio of the 18th term is required of both AP’s which is
Substituting n = 35 in (i) we get
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Arithmetic progression | Understanding the basics45 mins
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