Cho (x + y + z)² = x² + y²+ z². Chứng minh rằng: \[\frac{1}{{{x^3}}} + \frac{1}{{{y^3}}} + \frac{1}{{{z^3}}} = \frac{3}\]

Cho (x + y + z)² = x² + y²+ z².

Chứng minh rằng: \[\frac{1}{{{x^3}}} + \frac{1}{{{y^3}}} + \frac{1}{{{z^3}}} = \frac{3}\]

Cho (x + y + z)2 = x2 + y2 + z2. Chứng minh rằng: \[\frac{1}{{{x^3}}} + \frac{1}{{{y^3}}} + \frac{1}{{{z^3}}} = \frac{3}\]