a=[√(5-2√6)-√(5+2√6)]²
√(5-2√6)=√(5-√24)
[tex] \sqrt{5- \sqrt{24} } = \sqrt{ \frac{5+ \sqrt{25-24} }{2} } - \sqrt{ \frac{5- \sqrt{25-24} }{2} } [/tex]
√(5-√24)=√3-√2
√(5+2√6)=√(5+√24)
[tex] \sqrt{5+ \sqrt{24} } = \sqrt{ \frac{5+ \sqrt{25-24} }{2} } + \sqrt{ \frac{5- \sqrt{25-24} }{2} } [/tex]
√(5+√24)=√3+√2
(√3-√2-√3-√2)²=(-2√2)²=8∈N
