Question

Chứng minh:

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

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

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

Answer 1

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

Ta có: VP=(a+c)-(b+d)=a+c-b-d=(a-b)+(c-d)=VT

=> VT=VP (đpcm)

b. Ta có: VT=a(b+c)-b(a-c)=ab+ac-ab+bc=ac+bc=c(a+b)=VP

=> VT=VP (đpcm)

c. Ta có: VT=(a+b)(c+d)-(a+d)(b+c)=ac+ad+bc+bd-ab-ac-bd-cd=ad+bc-ab-cd

VP=(a-c)(d-b)=ad-ab-cd+bc=ad+bc-ab-cd=VT

=> VT=VP (đpcm)

Answer 2

Chtt có đó tick mình nha

Answer 3

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

​a - b + c - d = a + c - b - d

​a + c - b - d = a + c - b - d​