Question

a=10,a19= 100, find d and s19​

Answer 1

Answer:

a = 10

a19 = 100

a + 18d = 100

10 + 18d = 100

18d = 100 - 10

18d = 90

d = 5

Sn = (n/2)(a + l)

where l is the last term.

Sn = (19/2)(10 + 100)

Sn = (19/2)(110)

Sn = 1045

Hope this helps you☺