-
1.2.3 p/q q≠0
6 p/q
1
1 2 2 2 p/q p q p=2q
p2=2q2⑴
p2 q2 p2 p=2r ⑴ ⑴ ⑴ 4r2=2q2 2r2=q2
q2 q p q p q p/q 2
p/q 2