Answer:√5 - √2
Step-by-step explanation:
= √(5 + 2 - 2√10 )
= √{(√5)² +(√2)² - 2.√5.√2}
= √(√5 - √2)² (by identity a² + b² -2ab = ( a-b)²)
= √5 - √2
5√5 = 11.8033989 or -2√5+7