解；
x-3y=3
(x-3)(y+1)=5
∴xy+x-3y-3=5
∴xy=8-3=5
(x²-3)(3y²-1)
=3x²y²-x²-9y²+3
=3*5²-[(x-3y)²+6xy]+3
=75-(9+6*5)+3
=75-39+3
=36+3
=39