Question

how many terms of the AP 5, 8, 11, ... should be taken so that their sum is 670?
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Answer 1

Answer:

Hii Friend,

AP = 5,8,11

here,

First term (A) = 5

common difference (D) = 3

Sn = N/2 × [ 2A + (N-1) × D]

S20 = 20/2 × [2× 5 + (20-1) × 3]

=> 10 × (10 + 57)

=> 10 × 67 = 670.

HOPE IT WILL HELP YOU...... :-)

Answer 2

this app was not supporting so I had to take a screen shot

hope it helps u