Mathematics
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 AP :
S. No. | 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 | -------- |
AP
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Answer
(i) By formula,
an = a + (n - 1)d
Substituting values we get :
an = 7 + 3(8 - 1)
= 7 + 3 × 7
= 7 + 21
= 28.
Hence, an = 28.
(ii) By formula,
an = a + (n - 1)d
Substituting values we get :
⇒ 0 = -18 + (10 - 1)d
⇒ 0 = -18 + 9d
⇒ 9d = 18
⇒ d = = 2.
Hence, d = 2.
(iii) By formula,
an = a + (n - 1)d
Substituting values we get :
⇒ -5 = a + (18 - 1)(-3)
⇒ -5 = a + 17 × -3
⇒ -5 = a - 51
⇒ a = 51 - 5 = 46.
Hence, a = 46.
(iv) By formula,
an = a + (n - 1)d
Substituting values we get :
⇒ 3.6 = -18.9 + (n - 1)(2.5)
⇒ 3.6 = -18.9 + 2.5n - 2.5
⇒ 3.6 = 2.5n - 21.4
⇒ 2.5n = 21.4 + 3.6
⇒ 2.5n = 25
⇒ n = = 10.
Hence, n = 10.
(v) By formula,
an = a + (n - 1)d
Substituting values we get :
an = 3.5 + 0(105 - 1)
= 3.5 + 0 × 104
= 3.5 + 0
= 3.5
Hence, an = 3.5
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Related Questions
For the following APs, write the first term and the common difference:
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(iii) , …….
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Which of the following are APs ? If they form an AP, find the common difference d and write three more terms.
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(v) 3, 3 + , ……….
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(vii) 0, -4, -8, -12, ……..
(viii)
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(x) a, 2a, 3a, 4a, ……….
(xi) a, a2, a3, a4, ………..
(xii) ………..
(xiii) ………..
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