Tính:

B = \(\dfrac{\text{(a^2 +b^2 +c^2)*(a+b+c)^2+(a*b+b*c+c*a)^2}}{\left(a+b+c\right)^2-\left(a\cdot b+b\cdot c+c\cdot a\right)}\)

C = \(\dfrac{\left(b-c\right)^3+\left(c-a\right)^3+\left(a-b\right)^3}{a^2\cdot\left(b-c\right)+b^2\cdot\left(c-a\right)+c^2\cdot\left(a-b\right)}\)

Tính:

A = $\frac{a^2}{a+b}+\frac{b^2}{b+c}+\frac{c^2}{c+a}-\frac{b^2}{a+b}-\frac{c^2}{b+c}-\frac{a^2}{c+a}$