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Ans. (c) 20
Explanation:
A.P. = 1,4,7,10………
Here, first term (a) = 1
And common difference (d) = 4 - 1 = 3
Let nth term of the given A.P. is 58.
⇒ 58 = a + (n-1)d
⇒ 58 = 1 + (n-1)× 3
⇒ n - 1 = \dfrac{57}{3} = 19 \\
⇒ n = 20
So, 58 is 20th term of the A.P.
Ans. (c)
Explanation:
\text{sum of 25 terms of an A.P.} \\[4.5 bp]
\dfrac{-2}{3}, \dfrac{-2}{3},\dfrac{-2}{3} is \\[4.5 bp]
= \dfrac{n}{2} [2a+(n-1)d] = \dfrac{25}{2} \\[4.5 bp]
\begin{bmatrix} 2 × \left(\dfrac{-2}{3}\right) + (25 - 1 ) × 0\end{bmatrix} \\[4.5 bp]
= \dfrac{}{}\begin{bmatrix} -\dfrac{4}{3}\end{bmatrix} = \dfrac{-50}{3}
Explanation:
Let, a and d be the first term and common difference of the given A.P.
Then, a_4 = 8 \space and \space a_6 = 14 \space (Given)\\
⇒ a + 3d = 8 ...(i)
and a + 5d = 14 ...(ii)
On subtracting equation (i) from (ii),
we get,
2d = 6
⇒ d = 3On putting d = 3 in equation (i),
we get,
a + 3 × 3 = 8
⇒ a = 8 – 9 = – 1
(a) First term (a) = – 1. Ans.
(b) Common difference (c) Sum of first 20 terms (S20) (d) = 3. Ans.
∵ S_n = \dfrac{n}{2} [2a+(n–1)d] \\[4.5 bp]
∴ S_{20} = \dfrac{20}{2} [2× (-1) +(20–1)×3] \\
= 10(-2 + 57 )
= 550.
Explanation:
Here a = 10, d = 7 – 10 = – 3
and last term l = – 62
10th term from the last term
i.e., n = 10
Required term = l – (n – 1) d
= – 62 – (10 – 1) (– 3)
= – 62 + 27
= – 35
Therefore, the 10th term from the last term is – 35.
Explanation:
Let a be the first term and d be the common difference of the A.P. Then from the formula :
t_n = a + (n–1)d,\\[4.5 bp]
\text{we have,} \\[4.5 bp]
t_{10} =a + (10–1)d = a + 9d \\[4.5 bp]
t_{31} = a + (31–1)d = a + 30d \\[4.5 bp]
\text{we have,}\\[4.5 bp]
a + 9d = – 15 …(i) \\[4.5 bp]
a + 30d = –57 …(ii)\\[4.5 bp]
Solve equations (i) and (ii) to get the values of a and d.
Subtracting (i) from (ii), we have
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Download NowChapter No. | Chapter Name |
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Chapter 1 | Goods and Service Tax (GST) |
Chapter 2 | Banking |
Chapter 3 | Shares and Dividends |
Chapter 4 | Linear inequations |
Chapter 5 | Quadratic Equations in one variable |
Chapter 6 | Ratio and proportion |
Chapter 7 | Factorization |
Chapter 8 | Matrices |
Chapter 9 | Arithmetic Progression |
Chapter 10 | Geometric Progression |
Chapter 11 | Coordinate Geometry |
Chapter 12 | Reflection |
Chapter 13 | Similarity |
Chapter 14 | Loci |
Chapter 15 | Circles |
Chapter 16 | Constructions |
Chapter 17 | Mensuration |
Chapter 18 | Trigonometry |
Chapter 19 | Statistics |
Chapter 20 | Probability |
Chapter Wise Important Questions for ICSE Board Class 10 Mathematics |
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Goods and Service Tax (GST) |
Banking |
Shares and Dividends |
Linear inequations |
Quadratic Equations in one variable |
Ratio and proportion |
Factorization |
Matrices |
Arithmetic Progression |
Geometric Progression |
Coordinate Geometry |
Reflection |
Similarity |
Loci |
Circles |
Constructions |
Mensuration |
Trigonometry |
Statistics |
Probability |
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