but you have 6 terms in that range,
so the common difference
= d
= -5
or
use the formulas which you must have and know to do this topic
term15 = a+14d = -67
term21 = a + 20d = -97
subtract them :
6d = -30 , see above
d = -5
in a+14d = -67
a - 70 = -67
a = 3
term 30 = a + 29d
= 3 + 29(-5) = -142
The 15th and 21st terms of an arithmetic sequence are -67 and -97. What is the 30th term?
This is all I can figure out?
-97- (-24)= -30 common difference.
HELP!
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