Question

tìm x biết: (2x+1)+(2x+2)+......+(2x+2015)=0

Answer 1

(2x + 1) + (2x + 2) + ... + (2x + 2015) = 0

=> 2x + 1 + 2x + 2 + ... + 2x + 2015 = 0

=> 2015.2x + (2015 + 1).2015 : 2 = 0

=> 4030x + 2031120 = 0

=> 4030x = -2031120

=> x = -504

Answer 2

( 2x + 1 ) + ( 2x + 2 ) + ... + ( 2x + 2015 ) = 0

=> ( 2x + 2x + ... + 2x ) + ( 1 + 2 + .. + 2015 ) = 0

        2015 chữ số 2x

=> 2x . 2015 + 2031120 = 0

=> 2x . 2015 = 0 - 2031120

=> 2x . 2015 = - 2031120

=> 2x = ( - 2031120 ) : 2015

=> 2x = - 1008

=> x = ( - 1008 ) : 2

=> x = - 504

Chúc bạn học tốt nha !!!