Question

[Trần Thị Khánh Linh]

Chứng tỏ:

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

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

3/ -( a+b-c) + (a-b-c) = -2b

4/ a(b+c) - a(b+d) = a(c-d)

5/ a(b-c) + a(d+c) = a(b+d)

Answer 1

[Lê Phương Nga]

1/ ( a-b + c) - ( a + c )

= a - b + c - a - c 

= a - a  + c - c - b 

= -b 

2/ ( a  +  b ) - ( b - a ) + c 

= a + b - b + a + c 

= a + a + b - b + c

= 2a + c

3/ -( a + b - c ) + ( a-b-c )

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

= -a - b + c + a - b - c 

= -a + a + c -c - b - b 

= -2b

4 / a ( b+ c) - a ( b+ d )

= ab + ac - ab  + ad

= a ( b + c - b + d )

= a ( c + d)

Cứ lm thế bn nhé ! 

Answer 2

[Huy Hoang]

a, ( a - b + c ) - ( a + c )

= a - b + c - a - c

= a - a + c - c - b

= -b

#hoc_tot#