Question

tinh nhanh

A=-1+3-5+7-9+...+2015-2017

B=2-4-6+8+10-12-14+16+...+98-100+102+104

Answer 1

B = ( 2 - 4 - 6 + 8 ) + ( 10 - 12 - 14 + 16 ) +......+ ( 98 - 100 - 102 + 104 ) 
B = 0 + 0 +....+ 0 ( 52 số 0 )
B = 0

Answer 2

A=1+(3-5)+(7-9)+...+(2015-2017)

A=1+(-2)+(-2)+...+(-2)

A=(-2)*1008+1

A=(-2014)+1

A=-2015