Question

Answer 1

a) 

Xét:

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

\(=ab-ac-ab-bc+ac-bc\)

\(=\left(ab-ab\right)+\left(ac-ac\right)-\left(bc+bc\right)\)

\(=-2bc-VP\left(đpcm\right)\)

b) 

Xét:

\(VT=a\left(1-b\right)+a\left(a^2-1\right)\)

\(=a-ab+a^3-a\)

\(=a^3-ab\)

\(=a\left(a^2-b\right)=VP\left(đpcm\right)\)

Answer 2

`c) VT = a(b-x) + x(a+b) = ab -ax + ax + bx = ab + bx = b(a+x) = VP (đpcm)`