Question

how many terms are there in AP 1 + 5 + 9 + ........+149

Answer 1

Step-by-step explanation:

In given sequence......

a = t1 = 1

t2 = 5

d = 5-1 = 4

tn = a +(n-1)d

149 = -3+ 4n

4n = 152

n = 38

Sn = n/2 [ 2a +(n-1) d]

S38 = 38/2 [2 + 37 × 4]

S38 = 38/2 [ 150 ]

S38 = 38 × 75

S38 = 2850

So ,1 + 5 + 9 + ........+149 = 2850

Hope it helps uh!

Answer 2

Answer:

a=1

d=a2-a1

d=5-1=4

an=149

n=?

an=a+(n-1)d

149=1+(n-1)4

149-1=4n-4

148+4=4n

152=4n

152/4=n

n=38

Total no. of terms in this AP is 38

n= no. of terms

a=first term

d= common difference

an= here an is last term..