Question

of three terms are in A.P and sum of all three terms is 21. Find 2nd term.​

Answer 1

Answer:

let the three term of A.P are a,a +d,a+2d. now , as per the question ,

a+a+d+a+2d=3a+3d=21

i.e. a+d=7or ,d=7-a

now,a(a+2d) -(a+d)=6

a{a+2(7-a)}-7=6

a{a+14-2a}=13

a{14-a}=13

14a-a2=13

a2-14a+13=0

by factorising,we get

a=13,1

d=7-a

for a= 13,1d=7-13,7-1= - 6 ,6

respectively

now,three are two A'p s a,a +d,a + 2d for

two values of a and d

13,7,1and1,7,13