Question

FIND THE NUMBER OF TERMS OF THE AP 18,31/2,13,.....-99/2.

PLZ...EXAM ON 3rd march

Answer 1

A.P :- 18 , 31/2 , 13 ..... - 99/2

a ( first term ) :- 18

d ( common difference ) :- - 5/2

an = - 99/2

n = ?

an = a + ( n - 1 )d

- 99/2 = 18 + ( n - 1 ) × ( - 5/2 )


$\frac{ - 99}{2} - 18 = \frac{ - 5n}{2} + \frac{5}{2}$

$\frac{ - 99 - 36}{2} = \frac{ - 5n + 5}{2}$

- 135 = - 5n + 5

- 135 - 5 = - 5n

- 140 = - 5n

28 = n


The last term is 28 !!

Answer 2

HEY MATE HERE IS YOUR ANSWER...