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)

(Mk cần gấp)

 

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 )

= 0 + 2b + 2(-c)[ - c - c = -c + ( -c )]

= 2b + 2(-c)

=2(b - c )(= 2 . [ b + ( - c ) ]  )

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

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

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

   B = 2a + 0 + 0

   B = 2a

Answer 2

a,A=a+b-a+b+a-c-a-c

=2b-2c-a

b,B=a+b-c+a-b+c-b-c+a-a+b+c

=2a+0b+0c