Question

in a garden There are 23 rose plants in the First row ,21 in the second row,nineteen in the third row and so,on there are 5 plants the last row how many rows are there of rose plants?

Answer 1

here's the solution in the picture

Answer 2

It is an AP with the sequence 23,21,19...

a = 23, d = 21 - 23 = -2.

We know that an = a + (n-1) d

                         5  = 23 + (n-1) * (-2)

                         5 = 23 - 2n + 2

                         5 = 25 - 2n

                         2n = 25 - 5

                          2n = 20

                            n = 10.

There are 10 rows of rose plants.


Hope this helps!