if 5th term of an ap is 12.5 and 8th term is 20,find d
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Answer:
d = 2.5
Step-by-step explanation:
The 5th term of an AP,
5th term = a + ( n-1 ) d
12.5 = a + ( 5-1 ) d
12.5 = a + 4d
4d = 12.5 - a _ ( I )
The 8th term of an AP,
8th term = a + ( n-1 ) d
20 = a + ( 8-1 ) d
20 = a + 7d
20 = a + 4d + 3d
20 = a + 12.5 - a + 3d ....from ( I )
20 = 12.5 + 3d
3d = 20 - 12.5
d = 7.5 / 3
d = 2.5
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