Question

Bài 1: Chứng tỏ :

( a - b -c ) - ( a + b - c ) + ( b - c - a ) - ( c - a -b ) + 5 = -2c + 5 

Answer 1

(a-b-c)-(a+b-c)+(b-c-a)-(c-a-b)+5

=a-b-c-a-b+c+b-c-a-c+a+b+5

=-2c+5

happy new year

Answer 2

( a - b - c ) - ( a + b - c ) + ( b - c - a ) - ( c - a - b ) + 5 = - 2c + 5 

Ta có : VT = ( a - b - c ) - ( a + b - c ) + ( b - c - a ) - ( c - a - b ) + 5

                = a - b - c - a - b + c + b - c - a - c + a + b + 5 

                = - 2c + 5 = VP

=> ( a - b - c ) - ( a + b - c ) + ( b - c - a ) - ( c - a - b ) + 5 = - 2c + 5 

k mk nha

thank you very much