How do you rationalize (2sqrt3-sqrt2)/ (5sqrt2+sqrt3)?

1 Answer
May 10, 2015

Given (2sqrt(3)-sqrt(2))/(5sqrt(2)+sqrt(3)), try multiplying both the top and the bottom by (5sqrt(2)-sqrt(3))

The numerator:

(2sqrt(3)-sqrt(2))(5sqrt(2)-sqrt(3))

=-2sqrt(3)sqrt(3)+9sqrt(2)sqrt(3)-5sqrt(2)sqrt(2)

=-2*3+9sqrt(2*3)-5*2

=9sqrt(6)-16

The denominator:

(5sqrt(2)+sqrt(3))(5sqrt(2)-sqrt(3))

=25sqrt(2)sqrt(2)-sqrt(3)sqrt(3)

=50-3

=47.

So (2sqrt(3)-sqrt(2))/(5sqrt(2)+sqrt(3)) = (9sqrt(6)-16)/47.