Question

rationalise the surd (√5+√2) to get a rational number

Answer 1

(√5+√2)
= (√5+√2) ( √5-√2)
= (√5)² - (√2)²
= 5-2
=3

Answer 2

product of two binomial quadratic surds is always rational.
multiply by conjugate rt(5)-rt(2)

$( \sqrt{5} + \sqrt{2} )( \sqrt{5} - \sqrt{2} ) = { { \sqrt{5} }^{2} - { \sqrt{2} }^{2} = 5 - 2 = 3 }$