\(\left(a-b+c\right)-\left(a+c\right)\)
\(=a-b+c-a-c\)
\(=>-b\left(đpcm\right)\)
1.
<=> a - b + c - a - c = -b
<=> -b = -b (đpcm)
2.
<=> a + b - b + a + c = 2a + c
<=> 2a + c = 2a + c (đpcm)
\(\left(a-b+c\right)-\left(a+c\right)\)
\(=a-b+c-a-c\)
\(=-b\left(đpcm\right)\)
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