Let a, b, c be the sides of a triangle. The least value of expressionE=ab+c−a+bc+a−b+ca+b−c is ___
Put x=b+c−a, y=c+a−b, z=a+b−c, then x, y, z>0 and 2a=y+z, 2b=z+x, 2c=x+yUsing A.M.≥G.M., we getE=12(y+zx+z+xy+x+yz)≥3(yx.zx.zy.xy.xz.yz)1/6=3
. If a,b,c are the sides of a non-equilateral triangle, then the expression (b+c–a)(c+a–b)(a+b–c)–abc is: