Question

1+2+.......+2001

please answer ​

Answer 1

Answer:

sigma n..=n(n+1)/2

2001×2002/2

2001×1001=2003001

Answer 2

HERE IS YOUR ANSWER ⤵️⤵️⤵️

Let a, d & n be the first term, common difference and no. of terms in the given AP.

a = 1

d = 2-1 = 1

an = 2001

n = ?

an = a+(n-1)d

=> 2001 = 1+(n-1)1

=> 2001 -1 = (n-1) 1

=> 2000 = n+1

=> 2000-1 = n

=> 1999 = n

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

=> S1999 = 1999/2 [2×1+(1999-1)1]

= 1999/2 [2+1998]

= 1999/2 × 2000

= 1999000

HOPE IT HELPS YOU !!