SOLUTION: Simplify each expression. Rationalize all denominators Assume that all variables are positive. (2 - sqrt5)(2 + sqrt5)

Algebra ->  Rational-functions -> SOLUTION: Simplify each expression. Rationalize all denominators Assume that all variables are positive. (2 - sqrt5)(2 + sqrt5)       Log On


   

Question 867961: Simplify each expression. Rationalize all denominators Assume that all variables are positive.
(2 - sqrt5)(2 + sqrt5)

Answer by ramkikk66(644) About Me  (Show Source):
You can put this solution on YOUR website!
Expression is
%282+-+sqrt%285%29%29+%2A+%282+%2B+sqrt%285%29%29
This is of the form (a + b)*(a - b). Using the identity
%28a+-+b%29%2A%28a+%2B+b%29+=+a%5E2+-+b%5E2
The answer is
2%5E2+-+5 = 4+-+5 = highlight%28-1%29
Hope you got it!