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2+4+6+8+10.......+200 (no calculator)

What is the sum of only the even numbers from 2 -200?

1 of formulaes will give u the answer

!) a_n= a₁ + (n-1)d

2) S_n= n(a₁ + a_n)/2

quickly:
2+4+6+8+10.......+200

What is the sum of only the even numbers from 2 -200

a=2
d=2
n=?
L=200
L=a+(n-1)d
200=2+(n-1)2
n=100..
Using Sn=n/2(a+L) to find the sum.
Sn=100/2(2+200)
Sn=10100

Kendzyma:
a=2
d=2
n=?
L=200
L=a+(n+1)d
200=2+(n+1)2
n=98..
Using Sn=n/2(a+L) to find the sum.
Sn=98/2(2+200)
Sn=9898.

At all at all not correct

quickly:
At all at all not correct

sign mistake. Modified.