Respuesta :

1. by rationalizing the denominator?

2.
(2sqrt5 + 3sqrt7) * (2sqrt5 + 3sqrt7) 
= 4 * 5 + 6 sqrt35 + 6 sqrt35 + 9 * 7 
= 20 + 63 + 12sqrt35 
= 83 + 12sqrt35