Answer:
3 -√5
Step-by-step explanation:
(√5 + 1) / (2 + √5)
Multiply top and bottom of the fraction by the conjugate of 2 + √5 which is 2 - √5.
By doing this we rationalise the denominator:
= (√5 + 1 ) * ( 2 - √5) / (2 + √5)(2 - √5)
= (√5 + 1 ) * ( 2 - √5)/ (4 - 2√5 + 2√5 - 5)
= (2√5 - 5 + 2 - √5) / (4 - 5)
= (√5 - 3) / -1
= 3 -√5
