(a) Find the total number of rows of candies,in which a=3, d=2, An=120, n=?
0) 12
(ii) 10
(ii) 14
(iv) 8
Answers
Answer:
An arithmetic progression is a list of numbers in which each term is obtained by adding a fixed number to the preceding term except the first term. Given below is the general form of an AP.
a, a + d, a + 2d, a + 3d, ...
Here, a is the first term.
d is the common difference. It can be positive, negative or zero.
Further an AP can be finite type where the number of terms are finite and an infinite AP where there are infinite numbers of terms. Exercise 5.1 tests the students on the basic concepts of arithmetic progression. Later in this next section students will find a detailed description of the nth term of an AP. There are different terms of an AP like the second term, third term, fourth term, etc.
The nth term an of the AP with first term a and common difference d is given by an = a + (n − 1)d.
The last term is denoted by l.
Various solved examples are given to make the problems of this chapter more comprehensible. Exercise 5.2 is given with multiple problems so that students can practice more about the same.
The next section explains how to find the sum of first n terms of an AP. This includes the sum of first n terms of the Arithmetic Progression and the sum of n terms when the first and the last term are given.
The sum of first n positive integers is given by: Sn = n(n + 1)/2
In exercise 5.3 different word problems are given which lay emphasis on the same concept - To find the sum of n terms of an AP. A few diagrammatic questions are also given which makes the exercise interesting. Exercise 5.4 is an optional exercise and is not from the examination point of view. Later, a summary of the chapter is provided and also a note to the reader is given.
Answer:
a =3 d=2 An=120
n ?
we know =
An=a+(n-1)d
120=3+(n-1)2
120-3=(n-1)2
117÷2=n-1
58.5+1=n
59.5 =n
since n cannot be negative or in decimal so this q is wrong