Q. Find the 9th term of the arithmetic sequence −2x−5,−5x−8,−8x−11,…Answer:
Identify common difference: Identify the common difference in the arithmetic sequence.The sequence is given by −2x−5, −5x−8, −8x−11, ...To find the common difference, subtract the first term from the second term:(−5x−8)−(−2x−5)=−5x−8+2x+5=−3x−3Subtract the second term from the third term:(−8x−11)−(−5x−8)=−8x−11+5x+8=−3x−3The common difference is −3x−3.
Find nth term formula: Use the common difference to find the nth term formula.The nth term of an arithmetic sequence can be found using the formula:an=a1+(n−1)dwhere an is the nth term, a1 is the first term, n is the term number, and d is the common difference.Here, a1=−2x−5 and d=−3x−3.
Substitute values for 9th term: Substitute the values into the nth term formula to find the 9th term. a9=a1+(9−1)da9=(−2x−5)+(8)(−3x−3)a9=−2x−5−24x−24a9=−26x−29
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