Question

x²=(2+√5)² + (2-√5)²

Answer 1

X²=4+5+4-5

logo:

x²=9-1

x²=8
x=√8
x=2√2

Answer 2

$x^{2} =(2+ \sqrt{5} )^{2} + (2- \sqrt{5} )^{2} \\ x^{2} = 2^{2} + ( \sqrt{5} )^{2} + 2^{2} -(\sqrt{5} )^{2} \\ x^{2} =4+ \sqrt{25} +4- \sqrt{25} \\ x^{2} =4+5+4-5 \\ x^{2} =8 \\ x= \sqrt{8} \\ x=2 \sqrt{2}$