Cho ax + by + cz = 0. Rút gọn A = $\frac{{bc{{\left( {y - z} \right)}^2} + ca{{\left( {z - x} \right)}^2} + ab{{\left( {x - y} \right)}^2}}}{{a{x^2} + b{y^2} + c{z^2}}}$ .

Cho ax + by + cz = 0.

Rút gọn A = $\frac{{bc{{\left( {y - z} \right)}^2} + ca{{\left( {z - x} \right)}^2} + ab{{\left( {x - y} \right)}^2}}}{{a{x^2} + b{y^2} + c{z^2}}}$ .

Cho ax + by + cz = 0. Rút gọn A = bc(y−z)2+ca(z−x)2+ab(x−y)2ax2+by2+cz2\frac{{bc{{\left( {y - z} \right)}^2} + ca{{\left( {z - x} \right)}^2} + ab{{\left( {x - y} \right)}^2}}}{{a{x^2} + b{y^2} + c{z^2}}}.