Question

determine Ap whose 3rd term is 5 and 7th term is 9

Answer 1

Hii friend,

Third term of an AP = 5

a+2d = 5

a = 5-2d.....(1)

Again,

Seventh term of an AP = 9

a+6d = 9.......(2)


Putting the value of A in equation (2)

a+6d = 9

5-2d +6d = 9

4d = 9-5

4d = 4

D = 4/4

d = 1.

Putting the value of D In equation (1)

a = 5-2d

a = 5-2 × 1 = 5-2 = 3

Therefore,

First term of an AP = 3

Second term = a+d = 3+1 = 4

Third term = a+2d = 3 +2 × 1 = 3+2 = 5

Four term = a+3d = 3 + 3 × 1 = 3+3 = 6

AP = a , a+d , a+2d , a+3d.....


=> 3 , 4 , 5 , 6......


HOPE IT WILL HELP YOU.... :-)

Answer 2

a3=a+(n-1)d and a7=a+(n-1)d
5=a+2d....(i) and 9=a+6d...(ii)
subtracting (i) from (ii)
4d=4
d=1
putting value of d in eqn (i)
a=5-2d=5-2=3
AP series is
a,a+d,a+2d,a+3d,a+4d,a+5d.........
3,4,5,6...........
hope it will help you
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