Question

100 + 98 + 96 + 94...... + 2 - 97 - 95 - 93 - 92 - 91...- 1

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Answer 1

 ( 100 + 98 + 96 + .......... + 4 + 2 ) - ( 97 + 95 + 93 +...... + 1 )

= [ ( 100+ 2 ) x 50 : 2 ] - [ ( 97 + 1 ) x 49 : 2 ]

= 2550 - 2401

= 149

Answer 2

=100+98-97+96-95+94-93+...+2-1

=100+1+1+1+..+1=100+49.1

=149

hok tốt