Q. Find the 9 th term of the arithmetic sequence 5x+8,−2x+13,−9x+18,…Answer:
Define Common Difference: To find the 9th term of an arithmetic sequence, we need to determine the common difference between consecutive terms and then use the formula for the nth term of an arithmetic sequence, which is an=a1+(n−1)d, where an is the nth term, a1 is the first term, n is the term number, and d is the common difference.
Calculate Common Difference: First, let's find the common difference d by subtracting the first term from the second term.d=(−2x+13)−(5x+8)d=−2x+13−5x−8d=−7x+5
Verify Consistency: Now, let's verify the common difference by subtracting the second term from the third term to ensure it is consistent.d=(−9x+18)−(−2x+13)d=−9x+18+2x−13d=−7x+5Since we got the same common difference, we can confirm that the sequence is arithmetic and the common difference is correct.
Find 9th Term: Next, we use the formula for the nth term of an arithmetic sequence to find the 9th term a9.a9=a1+(9−1)da9=(5x+8)+8(−7x+5)
Simplify Expression: Now, let's simplify the expression for the 9th term.a9=5x+8+8(−7x)+8(5)a9=5x+8−56x+40a9=−51x+48