the 3rd term of an arithmetic sequence is 9 and 10th term is 23 write its 20th term
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3rd term = a+2d = 9 -----1.
10th term = a+9d = 23 ----2.
Subtracting 1 from 2 :
a + 9d = 23
a + 2d = 9
- - -
7d = 14
==> d = 14/7 = 2
Put value of d in 1.
a+2X2 = 9
a = 9 - 4
a = 5
20th term = a+19d = 5 + 19X2
= 5 + 38 = 43
Step-by-step explanation:
Hope it helps you buddy :)
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