1.已知x²+y²+7 xy+-2求5x²-3xy-4y²-11xy-7x²+2y²的值1.已知x²+y²+7 xy+-2求5x²-3xy-4y²-11xy-7x²+2y²的值

1.已知x²+y²+7 xy+-2求5x²-3xy-4y²-11xy-7x²+2y²的值1.已知x²+y²+7 xy+-2求5x²-3xy-4y²-11xy-7x²+2y²的值
1.已知x²+y²+7 xy+-2求5x²-3xy-4y²-11xy-7x²+2y²的值
1.已知x²+y²+7 xy+-2求5x²-3xy-4y²-11xy-7x²+2y²的值

1.已知x²+y²+7 xy+-2求5x²-3xy-4y²-11xy-7x²+2y²的值1.已知x²+y²+7 xy+-2求5x²-3xy-4y²-11xy-7x²+2y²的值
5x²-3xy-4y²-11xy-7x²+2y²
=-2x²-2y²-14xy
=-2(x²+y²)-14xy
=-2×7-14×(-2)
=-14+28
=14

x^2+y^2=7,xy=-2
5x^2-3xy-4y^2-11xy-7x^2+2y^2
=-2x^2-14xy-2y^2
=-2(x^2+y^2)-14xy
=-2*7-14*(-2)
=-14+28
=14