Question

chứng tỏ: 

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

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

thế thôi nha chứ... còn nhiều lắm :P

Answer 1

\(\left(a-b+c\right)-\left(a+c\right)\)

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

\(=>-b\left(đpcm\right)\)

Answer 2

1.

<=> a - b + c - a - c = -b

<=>   -b                   = -b (đpcm)

2.

<=> a + b - b + a + c = 2a + c

<=>     2a + c            = 2a + c (đpcm)

Answer 3

\(\left(a-b+c\right)-\left(a+c\right)\)

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

\(=-b\left(đpcm\right)\)

Answer 4

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

= a - b + c - a - c

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

= 0 + 0 - b

= -b

2. ( a + b ) - ( b - a ) + c 

= a + b - b + a + c

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

= 2a + 0 + c

= 2a + c