Simplify
4
_____
3+ square root of 5
rationalizing denominators depends on the fact that
(a+b)(a-b) = a^2-b^2
So, if you multiply top and bottom by (3-√5), you have
4(3-√5)
--------------
(3+√5)(3-√5)
4(3-√5)/(9-5) = 3-√5
4
_____
3+ square root of 5
(a+b)(a-b) = a^2-b^2
So, if you multiply top and bottom by (3-√5), you have
4(3-√5)
--------------
(3+√5)(3-√5)
4(3-√5)/(9-5) = 3-√5