Question

The 8th term of an A.P. is -23 and its 12th term is -39. Find the A.P​

Answer 1

Answer:

Step-by-step explanation:

t8=-23       t12= -39

Tn=a+(n-1)*d

for t8=a+(8-1)*d

t8=a+7d

-23=a+7d       ...........(1)

for t12=a+(12-1)*d

t12=a+11d

-39=a+11d     ..............(2)

subtracting equation (2) from (1)

a+11d=-39

a+7d=-23

-   -      +

    4d=-16

    d=-16/4

 d= -4

put value of d in equation(1)

a+7d=-23

a+7(-4)=-23

a+(-28)=-23

a=-23+28

a=5

ap is =5,1,-3,-7...