Math, asked by salman371989, 4 months ago

In an A.P 3,7,11,15,........find the sum of 20th terms

Answers

Answered by Anonymous

4

Answer:

Sn=n/2+2a+(n-1)d

S21=21/2+2(3)+(21-1)4

S21=10.5+6+20x4

S21=16.5+80

S21=96.5

Step-by-step explanation:

hope it help you

Answered by deepakchhina11

0

As D=4
A1=3
A20=3+(20-1)4
=3+(19)4
=3+76
=79

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