Cho a,b,c đôi một khác nhau.cm
a)$$\frac{a^2}{(b-c)^2}+\frac{b^2}{(c-a)^2}+\frac{c^2}{(a-b)^2}\geq 2$$
b)$$\frac{(a+b)^2}{(a-b)^2}+\frac{(b+c)^2}{(b-c)^2}+\frac{(c-a)^2}{(c+a)^2}\geq 2$$
c)$$\frac{ab}{(a-b)^2}+\frac{bc}{(b-c)^2}+\frac{ca}{(c-a)^2}\geq -\frac{1}{4}$$
a)$$\frac{a^2}{(b-c)^2}+\frac{b^2}{(c-a)^2}+\frac{c^2}{(a-b)^2}\geq 2$$
b)$$\frac{(a+b)^2}{(a-b)^2}+\frac{(b+c)^2}{(b-c)^2}+\frac{(c-a)^2}{(c+a)^2}\geq 2$$
c)$$\frac{ab}{(a-b)^2}+\frac{bc}{(b-c)^2}+\frac{ca}{(c-a)^2}\geq -\frac{1}{4}$$