Question

in an matic progression if the first term is 8 and the common difference is 4 then the 9th term of an ap is ​

Answer 1

Answer:

Given A.P is

1,−2,−5,−8,....

hence the common difference is given by d=a  

n+1

​  

−a  

n

​  

 

by putting n=1 in above equation

d=a  

2

​  

−a  

1

​  

=(−2)−(1)

d=(−2−1)

d=−3

first term of this A.P is

a  

1

​  

=1

the nth term of this A.P is given by

a  

n

​  

=a  

1

​  

+(n−1)d

⟹a  

n

​  

=1+(n−1)(−3)

⟹a  

n

​  

=1−3n+3

⟹a  

n

​  

=4−3n….eq(1)

finding next four terms of A.P

1)     for finding the 5th term of sequence (a  

5

​  

)  put n=5 in eq(1)

⟹a  

5

​  

=4−3×5

⟹a  

5

​  

=4−15

⟹a  

5

​  

=−11

Step-by-step explanation:

take this sum as example and do the sum friend

Answer 2

Answer:

a9=40

Step-by-step explanation:

an=a+(n-1)d

a9=8+(9-1)4

a9=8+(8)4

a9=8+32

a9=40