Advertisements
Advertisements
प्रश्न
Find the sum given below:
34 + 32 + 30 + ... + 10
Advertisements
उत्तर
34 + 32 + 30 + ... + 10
For this A.P.,
a = 34
d = a2 − a1
= 32 − 34
= −2
l = 10
Let 10 be the nth term of this A.P.
l = a + (n − 1) d
10 = 34 + (n − 1) (−2)
−24 = (n − 1) (−2)
12 = n − 1
n = 13
Sn = `n/2(a+1)`
= `13/2(34+10)`
= `(13xx44)/2`
= 13 × 22
= 286
APPEARS IN
संबंधित प्रश्न
In a school, students thought of planting trees in and around the school to reduce air pollution. It was decided that the number of trees, that each section of each class will plant will be the same as the class, in which they are studying, e.g., a section of class I will plant 1 tree, a section of class II will plant 2 trees, and so on till class XII. There are three sections of each class. How many trees will be planted by the students?
A spiral is made up of successive semicircles, with centres alternately at A and B, starting with centre at A of radii 0.5, 1.0 cm, 1.5 cm, 2.0 cm, .... as shown in figure. What is the total length of such a spiral made up of thirteen consecutive semicircles? (Take `pi = 22/7`)
[Hint: Length of successive semicircles is l1, l2, l3, l4, ... with centres at A, B, A, B, ... respectively.]
Find the sum of all 3-digit natural numbers, which are multiples of 11.
Find the three numbers in AP whose sum is 15 and product is 80.
In an A.P. 19th term is 52 and 38th term is 128, find sum of first 56 terms.
If the sum of first n even natural numbers is equal to k times the sum of first n odd natural numbers, then k =
Suppose three parts of 207 are (a − d), a , (a + d) such that , (a + d) >a > (a − d).
The term A.P is 8, 10, 12, 14,...., 126 . find A.P.
The 11th term and the 21st term of an A.P are 16 and 29 respectively, then find the first term, common difference and the 34th term.
Find the middle term of the AP. 95, 86, 77, ........, – 247.
