Question

the sum of n term of A.p is 3n2+7n. find the first term and common differece .find qlsp the no. of terms which is equal to 160.​

Answer 1

Answer:

First term, a=S  

1

​  

=  

2

1

​  

(3+7)=5

Second term, a+d=S  

2

​  

−S  

1

​  

=  

2

1

​  

(12+14)−  

2

1

​  

(10)=8⇒d=3

⇒a  

n

​  

(n  

th

 term)=a+(n−1)d=5+3(n−1)=3n+2

a  

20

​  

=60+2=62.

Step-by-step explanation: