Question

[Huong Dang]

Chứng minh đẳng thức. (a,b thuộc Z)

a)(a-b)-(a+b)+(2a-b)-(2a-3b)=0

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

Answer 1

[✆✘︵07XO]

\(\text{( a-b)-(a+b)+(2a-b)-(2a-3b)=0}\)

\(\Leftrightarrow\text{ a-b-a-b+2a-b-2a+3b = 0}\)

\(\Leftrightarrow\text{0=0}\)

\(\Rightarrow\text{ĐPCM}\)

Answer 2

[๖²⁴ʱんuﾘ ｲú❄✎﹏]

\(\left(a+b-c\right)-\left(a-b+c\right)+\left(b+c-a\right)-\left(a-b-c\right)=2b\)

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

\(-2a+4b-2c=2b\)

\(-2a+4b-2c-2b=0\)

\(-2a+2b-2c=0\)

\(đpcm\)