Question

find the AP whose 7th and 13 from are respectively 34 and 64

Answer 1

T7 =a+6d. (i)
T13=a+12d. (II)
Now subtract equation II to I
a+12d=64
-a-6d=34
then we get
6d=30
therefore d=5.
now we put d=5 in first equation and we get first term...
then we can write AP.

Answer 2

Heya,

As per the question,

7th term = 34

=> a +6d = 34 --------(1)

13th term = 64

=> a+12d = 64 ------(2)

Eq(2) - eq(1)

a +6d = 34
(-)
a+12d = 64
____________
-6d = -30

6d =30

d =5

a + 6 (5) =34

a = 4

Therefore the A.P is 4,9,14,19...


Hope it helps u....