Question 758793
Hi,

To rationalize the denominator, you want to make sure that there is no radical sign in the denominator. In order to do so, you can multiply the denominator AND numerator by the conjugate of the denominator.

For example: 4/(3 + SQRT(7))

To rationalize, you multiply the denominator and numerator by (3 - SQRT(7)

[4(3 - sqrt(7)] / [(3 + sqrt(7))(3 - sqrt(7)]

= (12 - 4sqrt(7))/(9 - 7)

= (12 - 4sqrt(7)/ 2

= 6 - 2sqrt(7)

You can do the same for other problem.

By the ways, you always use the difference of two squares 

(a - b)(a + b) = a^2 - b^2

Message me if you need extra assistance for your math class.

John