a sequence starts a 200 and 30 is subtracted each time 200,170,140 what are the first two numbers in the sequence that are kess then zero

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Explanation:

a = 200 = first term

d = -30 = common difference

Tn = nth term

Tn = a + d(n-1)

Tn = 200 + (-30)(n-1)

Tn = 200 - 30n + 30

Tn = -30n + 230

Set Tn less than 0 and isolate n

Tn < 0

-30n + 230 < 0

230 < 30n

30n > 230

n > 230/30

n > 7.667 approximately

Rounding up to the nearest whole number gets us

So Tn starts to turn negative when n = 8

We can see that,

Tn = -30n + 230

T7 = -30*7 + 230

T7 = 20

and

Tn = -30n + 230

T8 = -30*8 + 230

T8 = -10 is the 8th term

and lastly

Tn = -30n + 230

T9 = -30*9 + 230

T9 = -40 is the ninth term

Or once you determine that T7 = 20, you subtract 30 from it to get 20-30 = -10 which is the value of T8. Then T9 = -40 because -10-30 = -40.