x+y=9 xy=16 x^2+y^2=?

已知x-xy=8,xy-y=-9,求x+y-2xy的值 x^+2xy+y^+4=16 x^-2xy+y^=16 求(3xy+6y^)+|x^-(2xy+2y^-3x^)|的值 已知x*x-4xy+4y*y=0 求[2x(x+y)-y(x+y)]/(4x*x-4xy+y*y)的值? 已知2x-3根号xy-2y=0(x>0),求x^2+4xy-16y^2/x^2+xy-9y^2 已知2X-3√xy-2y=0(x>0)求2x²+xy-9y²分之x²+4xy-16y
x^2+xy+x=36,y^2+xy+y=20,求x+y. 如果x^2+xy+y-14,y^@+xy+x=28,求x+y的值. （-3x^y+2xy)-( )=4x^+xy f（x+y,xy）=x^2+y^2 x*-2xy+3y*=9 4x*-5xy+6y*=30 已知xy=-2,x-y=3,求（x+y)（x-y)-y^2+（x-y)^2-（6x^2y-2xy^2)÷2y 已知x+y=-1,xy=-2,求代数式-5（x+y)+(x-y)+x(xy+y)的值