Question

if a=2 and d=4 then s20 =?​

Answer 1

Answer:

780

Step-by-step explanation:

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

given:

a=2

d=4

n=20

=) S20= 20/2 [2+(20-1) 4]

=) S20= 10 [2+ (19)4]

=) S20= 10 [2+76]

=) S20= 10 (78)

=) S20= 780

Answer 2

Answer:

800

Step-by-step explanation:

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