Question

plz ansew the question​

Answer 1

Answer:

option B is the answer.

Answer 2

Answer:

B

Step-by-step explanation:

Sum formula for AP

$n \div 2(2a + (n - 1)d))$

In this AP

1+2...

a=1

d=1

Placing the values we get

=n/2(2+(n-1))

=n(n+1)/2

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