a=10,a19= 100, find d and s19
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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☺
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