Question

cho (a+b+c+1)(a-b-c+1)=(a-b+c-1)(a+b-c-1)cmr a,b,c lap thanh 1 ti le thuc

Answer 1

<=> ((a+1)+(b+c))((a+1)-(b+c))=((a-1)+(c-b))((a-1)-(c-b))

<=> (a+1)^2 -(b+c)^2 =(a-1)^2 - (c-b)^2

<=> a^2 +2a+1-b^2-2bc-c^2= a^2-2a+1-c^2+2bc-b^2

<=> 4a=4bc

<=> a=bc

=>a/bc=1

=> đpcm