Question

find the sum of 27 terms in the AP 3,7,11

Answer 1

Answer:

Sn = n/2 {2a+(n-1)d}

n=27

a=3

d= 7-3

d=4

S27= 27/2{2(3)+(27-1)4}

27/2{6+26(4)}

27/2(6+104)

27/2(110)

27*55

1485

therefore,

sum of 27 terms of an AP is 1485.......

Answer 2

Answer:

Step-by-step explanation:

In a Given A.P ;

a = 3

d = 7-3 = 4

On the contrary let 144 be the nth term of A.P

Tn = 144

n = ?

Tn = a+(n-1)d

144 = 3+(n-1)4

n-1 = 141/4

n = 35.25+1

n = 36.25

As the value of n is a decimal or number, hence 144 is not the term of given A.P