Question

if third term of an AP is 11 and fifth term is 19 . find AP​

Answer 1

Step-by-step explanation:

If third term of an AP is 11 then we have, =a+2d=11----(1)

and If the fifth term of AP is 19 then we have,

=a+4d=19-----(2)

On solving (1) and (2) equation we get, d=4 and a=3

Hence, AP is 3, 7, 11, 15, 19.....

Answer 2

Step-by-step explanation:

The third term of AP (a3) = 11

And, Fifth term (a5) = 19

we know that,

a3 = a+ 2d

11 = a + 2d ------------ equation 1

then,

a5 = a + 4d

19 = a + 4d ------------equation 2

By using elimination method in equation 1 and 2 ,

a+4d = 19

a+2d = 11

-------------- (subtract)

2d = 8

d = 4 ------------------ equation 3

putting value of d in equation 1 we get,

a= 3 (first term. of AP)

second term (a2) = a+d

3+4= 7

fourth term (a4) = a+3d

15

Hence , AP is 3, 7, 11, 15, 19

with common difference 4