Question

Chứng minh các đẳng thức:

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

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

      Các bạn trả lời nhanh hộ mình :)

Answer 1

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

= a-b + c+d

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

=> (a-b) + (c+d) = (a+c) - (b-d)

b, (a-b) - (a-d) 

= a-b - a + d

= (a+d) - (b-d)

=> (a-b) - (a-d) = (a+d) - (b-d)

Answer 2

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

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

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

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

Vậy ...

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

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

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

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

Vậy ... 

Answer 3

Thanks