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प्रश्न
What is the sum of first 10 terms of the A. P. 15,10,5,........?
पर्याय
(A) -75
(B) -125
(C) 75
(D) 125
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उत्तर
(A) -75
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संबंधित प्रश्न
In an A.P., if S5 + S7 = 167 and S10=235, then find the A.P., where Sn denotes the sum of its first n terms.
Find the sum to n term of the A.P. 5, 2, −1, −4, −7, ...,
Find the sum of all integers between 100 and 550, which are divisible by 9.
Find the sum of the first 15 terms of each of the following sequences having the nth term as
bn = 5 + 2n
The first and the last terms of an A.P. are 34 and 700 respectively. If the common difference is 18, how many terms are there and what is their sum?
If the 8th term of an A.P. is 37 and the 15th term is 15 more than the 12th term, find the A.P. Also, find the sum of first 20 terms of A.P.
Determine the nth term of the AP whose 7th term is -1 and 16th term is 17.
If 4 times the 4th term of an A.P. is equal to 18 times its 18th term, then find its 22nd term.
The first three terms of an AP are respectively (3y – 1), (3y + 5) and (5y + 1), find the value of y .
If the ratio of sum of the first m and n terms of an AP is m2 : n2, show that the ratio of its mth and nth terms is (2m − 1) : (2n − 1) ?
Draw a triangle PQR in which QR = 6 cm, PQ = 5 cm and times the corresponding sides of ΔPQR?
Find the first term and common difference for the A.P.
127, 135, 143, 151,...
Find the sum of all 2 - digit natural numbers divisible by 4.
Q.13
Which term of the AP 3, 15, 27, 39, ...... will be 120 more than its 21st term?
Find the sum of natural numbers between 1 to 140, which are divisible by 4.
Activity: Natural numbers between 1 to 140 divisible by 4 are, 4, 8, 12, 16,......, 136
Here d = 4, therefore this sequence is an A.P.
a = 4, d = 4, tn = 136, Sn = ?
tn = a + (n – 1)d
`square` = 4 + (n – 1) × 4
`square` = (n – 1) × 4
n = `square`
Now,
Sn = `"n"/2["a" + "t"_"n"]`
Sn = 17 × `square`
Sn = `square`
Therefore, the sum of natural numbers between 1 to 140, which are divisible by 4 is `square`.
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The ratio of the 11th term to the 18th term of an AP is 2 : 3. Find the ratio of the 5th term to the 21st term, and also the ratio of the sum of the first five terms to the sum of the first 21 terms.
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An Arithmetic Progression (A.P.) has 3 as its first term. The sum of the first 8 terms is twice the sum of the first 5 terms. Find the common difference of the A.P.
