Question

$\frac{1}{ \sqrt{5}-2} + \frac{1}{ \sqrt{5}+2}$

Aratati ca a∈(√19, √21)

Answer 1

$\frac{ \sqrt{5}+2 }{5-4} + \frac{ \sqrt{5} -2}{5-4} =2 \sqrt{5}$
2√5=√20∈(√19,√21)