Question

If some of 8terms of an AP is first term is 4 find 12th term​

Answer 1

Answer:

a12 = -7

Step-by-step explanation:

Given: S8=4=a

a12=?

We know that

Sn=n[2a+(n-1)d]/2

4=8[2×4+(8-1)d]/2

4×2=8[8+7d]

8=8[8+7d]

8+7d=1

7d=-7

d = -1

a=4, d= -1

Now, an=a+(n-1)d

∴a12=4+(12-1)(-1)= 4-11=-7

∴a12 = -7