How do you find the sum of the arithmetic sequence given a1 = 5, d = 7, n = 120?

Pellagra3d

Pellagra3d

Answered question

2022-10-20

How do you find the sum of the arithmetic sequence given a1 = 5, d = 7, n = 120?

Answer & Explanation

Immanuel Brennan

Immanuel Brennan

Beginner2022-10-21Added 9 answers

The formula for the sum of an arithmetic sequence when a,d and n are given is:

S u m = ( n 2 ) [ 2 a + ( n - 1 ) d ]

Here : a 1 = 5 , d = 7 and n = 120

= ( 120 2 ) [ 2 . 5 + ( 120 - 1 ) . 7 ]

= 60 . [ 10 + 119 . ( 7 ) ]
= 60 . [ 10 + 833 ]
= 60 . ( 843 )
= 50580

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