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The 3rd term of an arithmetic progression is -9... - JAMB Mathematics 2010 Question

The 3rd term of an arithmetic progression is -9 and the 7th term is -29. Find the 10th term of the progression
A
-44
B
-165
C
165
D
44
correct option: a

3rd term : a + 2d = -9 .......(1)

7th term : a + 6d = -29 ......(2)

(2) - (1): 4d = -20

:. d = -20/4 = -5

From (1) : a + 2(-5) = -9

       a - 10    = -9<br />

:. a = -9 + 10 = 1

:. 10th term of A.P is a + 9d = 1 + 9 (-5)

= 1 - 45 = -44

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