Question

the sum of the third and the seventh terms of an ap is 6 and their product is 8 find the sum of the first sixteen terms of an ap​

Answer 1

Step-by-step explanation:

let the third term be A + 2D

and the 7th term be A + 6D

according to the questions

A+2D+A+6D=6

A+4D=3

A + 2D=3-2D

A+6D=3+2D

and

(A+2D) x (A+6D) = 8

(3-2D) x ( 3+2D)=8. (using above relation)

on solving this equation

we get,. D= +1/2 or -1/2

we shall use the positive value

now putting the value of D in the given equation

we have

A + 4D=3

A=1

now the sum of first 16 terms will be

S=16/2{1+15x1/2}=8x17/2=68

the required answer will be 68

if this answer does not match then you should try with the negative value of D if it is matched then please mark this as brainliest answer

Answer 2

Answer:

hey here is your answer in above pics

pls mark it as brainliest

Step-by-step explanation:

hey ur answer 76 or 20