Question

 

tinh nhanh

 

 

2-4+6-8+...=2014-2016

 

Answer 1

Ta có : 2 - 4 + 6 - 8 + ...... + 2014 - 2016 

= 2 - 4 + 6 - 8 + ...... + 2014 - 2016 

= (2 - 4) + (6 - 8) + ...... + (2014 - 2016)

= -2 + -2 + ..... + -2

= -2 x 1008

= -2016

Answer 2

= - 2016

Answer 3

 Ta có : 2 - 4 + 6 - 8 + ... + 2014 - 2016

= (2 - 4) + ( 6-8 ) +... + ( 2014 - 2016 )

= (-2) + ( - 2) + ... + (- 2 )

= ( - 2 ) x 1008

= - 2016