Question

2) Qual a soma dos 200 primeiros números pares?
-) 40200
b) 80400
c) 60300
d) 50500
e) 39.800​

Answer 1

a1=2

r=4-2=2

an=200

n=200-1

sn=?

an=a1+(n-1).r

=2+(200-1).2

=2+199.2

=400

sn=(2+400).200 /2

sn=402.200/2

sn=40200

Answer 2

resolução!

an = a1 + ( n - 1 ) r

an = 2 + ( 200 - 1 ) 2

an = 2 + 199 * 2

an = 2 + 398

an = 400

Sn = ( a1 + an ) n / 2

Sn = ( 2 + 400 ) 200 / 2

Sn = 402 * 100

Sn = 40200