Question

please answer this as fast as you can

Answer 1

115,110,105,_100___

reason:- 115-5=110,110-5=105,105-5=100 is sure right answer.



@@@@@@ please marks brilliance.

Answer 2

Let a be the first term and d be a common difference.

Given the first term a = 115.

common difference d = t2 - t1

                                      = 110 - 115

                                      = -5.

We know that sum of n terms of an AP sn = a + (n - 1) * d

= > 115 + (n - 1)(-5)

= > 115 - 5n + 5

= > 120 - 5n.


Now, we have to find the suitable value of n so that the value of 120 - 5n is negative.


Let n = 21, we get

nth term = 120 - 5n

               = 120 - 5(21)

               = 105.


Let n = 23, we get

nth term = 120 - 5n

               = 120 - 5(23)

               = 120 - 115

               = 5.


Let n = 24, we get

nth term = 120 - 5n

               = 120 - 5(24)

               = 120 - 120

               = 0.


Let n = 25, we get

nth term = 120 - 5n

               = 120 - 5(25)

               = 120 - 125

               = -5.


Therefore the 25th term is negative.


Hope this helps!