Question

2. (1) Write an A.P in which a-10 & d in any natural number.
ii) Find the sum of the first ten terms using formula.
(iii) Can -80 be a term of this A.P? Justify.​

Answer 1

Answer:

Let Initial term =a, Diference =d

a,d∈N

S  

20

​  

=  

2

20

​  

[2a+19d]=10(2a+19d)

116.2>2a+19d>107.2                          _________(1)

Also given a+5d=32    [Since sixth term so using formula for the nth terms a  

6

​  

=a+5d]

⇒a=32−5d                                    ___________.(2)

With (1) and (2), 116.2>64+9d>107.2

∴52.2>9d>43.2

∴d=5 as d∈N, a=7

As the term in AP are natural numbers.

Step-by-step explanation: