Short Answer TypeThe number of rose plants in the rows are 23, 21, 19, .......... 5
Here, a = 23, d = –2, an = 5
We know that,an = a + (n – 1)d
⇒ 5 = 23 + (n – 1) (–2)
⇒ 5 = 23 – 2n + 2
⇒ 5 = 25 – 2n
⇒ 2n = –20
⇒ n = 10
Hence, there are 10 rows in the flower bed.
Long Answer TypeShort Answer TypeThe first and the last term of an A .P. are 4 and 81 respectively. If the common difference is 7, how many terms are there in the A .P. and what is their sum?
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