Question

Chứng tỏ 

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

Answer 1

(a - b + c) - (a + c) 

= a - b + c - a - c

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

= -b   

Answer 2

Ta có: \(\left(a-b+c\right)-\left(a+c\right)=-b\)

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

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

\(\Leftrightarrow0+0-b=-b\)

\(\Leftrightarrow-b=-b\left(đpcm\right)\)

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