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# Fill in the blanks in the following table, given that a is the first term, d the common difference and an the nth term of the A.P. a d n an I 7 3 8 …... II − 18 ….. 10 0 III ….. − 3 18 − 5 IV − 18.9 2.5 ….. 3.6 V 3.5 0 105 …..

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Solution

## I. a = 7, d = 3, n = 8, an = ? We know that, For an A.P. an = a + (n − 1) d = 7 + (8 − 1) 3 = 7 + (7) 3 = 7 + 21 = 28 Hence, an = 28 II. Given that a = −18, n = 10, an = 0, d = ? We know that, an = a + (n − 1) d 0 = − 18 + (10 − 1) d 18 = 9d Hence, common difference, d = 2 III. Given that d = −3, n = 18, an = −5 We know that, an = a + (n − 1) d −5 = a + (18 − 1) (−3) −5 = a + (17) (−3) −5 = a − 51 a = 51 − 5 = 46 Hence, a = 46 IV. a = −18.9, d = 2.5, an = 3.6, n = ? We know that, an = a + (n − 1) d 3.6 = − 18.9 + (n − 1) 2.5 3.6 + 18.9 = (n − 1) 2.5 22.5 = (n − 1) 2.5 Hence, n = 10 V. a = 3.5, d = 0, n = 105, an = ? We know that, an = a + (n − 1) d an = 3.5 + (105 − 1) 0 an = 3.5 + 104 × 0 an = 3.5 Hence, an = 3.5  Suggest Corrections  3      Similar questions  Explore more