Mathematics · Chapter 5 · NCERT Examples
Verified NCERT questions and solutionsSolutions are checked independently and follow the supplied NCERT chapter edition.
Rows of a flower bed contain 23,21,19,…,5 rose plants. Find the number of rows.
Solution
Board-exam working:
The row counts form an AP with a=23,d=21−23=−2 and last term l=5.
Use l=a+(n−1)d: 5=23+(n−1)(−2)=23−2n+2=25−2n.
Thus 2n=20 and n=10.
Check: a₁₀=23+9(−2)=23−18=5.