Question

докажите тождество (х2 + у2-z2 )+(x2+z2-y2)-(x2-z2)=x2+z2

Answer 1

(х² + у²-z² )+(x²+z²-y²)-(x²-z²)=x²+z²
(х² + у²-z² )+(x²+z²-y²)-(x²-z²)=х² + у²-z²+x²+z²-y²-x²+z²)=х²+z² ч.т.д.