Question

pls solve this and you will be marked brainly

Answer 1

your answer is in above attachment

Hope it helps you dear

Answer 2

Step-by-step explanation:

Series is

a1= -1 + 4 = 3

a2 = 4 -9 = -5

a3 = -9 + 16

a1000 = 1000^2 - 1001^2 = -1 ( 2001) = -2001

So S

= ( 3+7+11 …1999 ) -( 5+9+13….2001)

Say S1-S2

First lets evaluate S1

1999 = 3 + (n-1) 4

Or n = 500

S1 = 250 ( 2002) = 500,500

Now S2 :

2001 = 5 + (n’-1) 4

n' = 500

S2 = 250(2006 ) = 501,500

S= S1 -S2 = -1000