已知a-b=1,ab=3,求（a方-2）（b方-2）的值

(a^2-2)(b^2-2)
=(ab)^2-2(a^2+b^2)+4
=(ab)^2-2[(a-b)^2+2ab]+4
a-b=1,ab=3
=9-2(1+6)+4
=-1

(a²-2)(b²-2)
=a²b²-2a²-2b²+4
=(ab)²-2(a²+b²)+4
=(ab)²-2[(a-b)²+2ab]+4
=(ab)²-2(a+b)²-4ab+4
=3²-2×1²-4×3+4
=9-2-12+4
=-1

ab=3
a^2*b^2=9
a-b=1
(a-b)^2=1
a^2+b^2=1+3*2=5
原式=a^2*b^2-2a^2-2b^2+4=9-10+4=3

-1