Question

which of the following is not irrational number 5+√5 , (2+√5) √5 , (2+√5) (2-√5) , 5√5​

Answer 1

Answer:

(2+√5)(2-√5) is not irrational.

Step-by-step explanation:

This is because when we simplify it by using (a+b)(a-b) identity we get:

(a+b) (a-b) = a² - b²

(2+√5) (2-√5) = (2)² - (√5)² = 4 - 5 = -1