Question

Bỏ dấu ngoặc rồi thu gọn biểu thức :                                                                                             

a) A = ( a + b ) - ( a - b ) + ( a - c ) - ( a + c )

b) B = ( a + b - c ) + ( a - b + c ) - ( b + c - a ) - ( a - b - c )

Answer 1

a/ A= ( a + b ) - ( a - b ) + ( a - c ) - ( a + c )

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

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

= 2b + ( -2c )

= 2b - 2c

 

b/ B= ( a + b - c ) + ( a - b + c ) - ( b + c - a ) - ( a - b - c )

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

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

= 2a

Answer 2

a) A=a+b-a+b+a-c-a-c

A=2b

b)B=a+b-c+a-b+c-b-c+a-a+b+c

B=4a+b