Question

For a given A.P., S20=100 and d= -2. Find the first term(a) of this A.P.,

Answer 1

Answer:

Step-by-step explanation:

S20=100

D=-2

10(2a+19*-2)=100

2a-38=100/10

2a=10+38

a=48/2

a=24

Answer 2

Answer:

Step-by-step explanation:

Given

S20=100

We lnow tha

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

S20=20/2(2a+(20-1)(-2))

S20=20/2(2a+(19)(-2))

100=10(2a-38)

100/10=2a-38

10=2a-38

10+38=2a

48=2a

24=a

There fore the first term of the ap is 24