Ta có:
\(B=2-4-6+8+10-12-14+16+...+2002-2004-2006+2008\)
\(\Rightarrow B=\left(2-4-6+8\right)+\left(10-12-14+16\right)+...+\left(2002-2004-2006+2008\right)\)
( 251 cặp số )
\(\Rightarrow B=0+0+...+0\)
\(\Rightarrow B=0\)
Vậy B = 0
B=2-4-6+8+10-12-14+16+.....+2002-2004-2006+2008
B=(2-4-6+8)+(10-12-14+16)+.....+(2002-2004-2006+2008)
B= 0 + 0 + 0 + ........ + 0
B= 0
xong rồi đó bạn. Nhớ tích cho nha I