Question

已知x(x-1)-(x²-y)=2,求代数式[（3x²+3y²）\2]-3xy

Answer 1

x(x-1)-(x²-y)=2

x²-x-x²+y=2

x-y=-2

[（3x²+3y²）2]-3xy

=(3x²-6xy+3y²)/2

=3(x-y)²/2

=6