# Are these polynomials?

Algebra Level 2

$\large \frac { { x }^{ 2 }+{ y }^{ 2 }+{ z }^{ 2 }-yz-zx-xy }{ { a }^{ 2 }+{ b }^{ 2 }+{ c }^{ 2 }-bc-ca-ab }$

If $$x=b+c, y=c+a, z=a+b$$, then find the value of the expression.

Hint: See how you can use the identity of $${ \left( a-b \right) }^{ 2 }$$.

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