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How to find Sum of First N Terms of an Arithmetic Sequence - First Term and N GivenItsMyAcademy.com

How to find Sum of First N Terms of an Arithmetic Sequence – First Term and N Given

How to find Sum of First N Terms of an Arithmetic Sequence – First Term and N Given


In previous video lesson we learned the formula for the sum of the arithmetic progression or sum of arithmetic sequence.

Now in this video lesson we are going to learn application of the sum of nth term of an Arithmetic progression formula.

Let me write the formula for sum of nth term of an Arithmetic progression once again here:
1. Sum of n terms of Arithmetic progression = [n {2a + (n-1)d} ] /2
2. Sum of n terms of Arithmetic progression = [n(a + l )]/2
Now, lets learn the application of the formula. I hope you are watching this video with pen and note book with you.
If you feel small screen size then please view it in full screen it will be nice.
Let’s begin.





Well how was it friend?

Here in this problem we have got the first term, common difference and total number of terms in Arithmetic progression. We need to find the sum of this Arithmetic progression.

Just put all the values in the formula Sum of n terms of AP = [n {2a + (n-1)d} ] /2 one by one you will get the sum of the arithmetic sequence.

 

Here are some exercise based on the sum of n term of the arithmetic progression. Please try to solve these problems it will really boost you in the topic. If you feel any problems please comment .

 

Q1. Find the sum of 20 terms of arithmetic sequence 1, 4, 7, 10, …….. (Ans = 590)

Q2. If nth term of an Arithmetic progression is (2n+1), find the sum of first n terms of the Arithmetic progression. (Ans = n (n+2) )

Q3. Find the sum of first 30 terms of an arithmetic progression whose second term is 2 and seventh term is 22. (Ans = 1680)

Q4. Find the sum of the following arithmetic progressions:
1. 50, 46, 42, ………………….to 10 terms . (Ans = 320)

2. 3, 9/2, 6, 15/2, ………………………to 25 terms. (Ans = 525)

3. 41, 36, 31, …………….to 12 terms. (Ans = 162)

4. a+b, a-b, a-3b, …………to 22 terms. (Ans = 22a – 440b)

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