Question

1. A series is given by 51 + 50 + 49 + ... + 21.
How many terms are there in this series?
2. What is the 27th positive odd number
3. Which of the following cannot be the general
term of an AP ?
4n +3, 3n2 + 5, 2n – 4
,2n-4/5
Check whether - 140 is a term of the A.P. :​

Answer 1

Answer:

1.Given:First term(a)=51

common difference is (-1)

last term is 21.

RTF:n=?

proof:according to general form of a term i.e.,t of n =a+(n-1)d

21=51+(n-1)(-1)

21=51-n+1

n=52-21

n=31

Answer 2

Answer:

refers to the attachment