Question

Chứng minh đẳng thức sau :

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

Answer 1

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

Ta có :

( a - b ) - ( c - d ) + ( b + c ) = a - b - c + d + b + c = a + b - b + c - c + d = a + ( b - b ) + ( c - c ) + d = a + 0 + 0 + d = a + d

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

Answer 2

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