Q4 of 202 Page 10

Write the value of a30 – a10 for the A.P. 4, 9, 14, 19, ……….

Here a1 = 4

a2 = 9


a3 = 14


d = common difference = a3 – a2 = a2 – a1 = 14 – 9 = 9 – 4 = 5


a30 = a + (n–1) d


a30 = 4 + (30 –1) 5


a30= 4 + 29 X 5


a30= 149


Similarly, a10 = 4 + 9x5


a10= 49


a30 – a10 = 149 – 49 = 100


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