若x/y=2/7则7x²-3xy+2y²/2x²-3xy+7y²=
已知x²-3xy+4x=3,y²+xy-4y+7=0,则xy-1/2(x²+y²
已知xy²=-6,求xy(x^3y^7-3x^2y^5-11.5y)的值
若x/y=2/7则7x²-3xy+2y²/2x²-3xy+7y²=
若x/y=2/7,则7x²-3xy+2y²/2x²-3xy+7y²
已知x/2=y/3(xy≠0),求x²-2xy-3y²/x²-6xy-7y²的值
若x²+y²=7,xy=-2,求5x²-3xy-4y²-11xy-7x²
计算:(-7x²y)(2x²y-3xy³+xy)
若x=1/2,y=1 求x(x²+xy+y²)-y(x²+xy+y²)+3xy(
已知X/Y=2,则X²+2XY-3Y²/X²-XY+Y²=?
已知x-7y=0,且y≠0,求2x²﹢xy-3y²分之x²-3xy+y²的值
已知x/y=2/7,则x²-3xy+2y²/2x ²-3xy+7y²的值是()
已知x/y=2/7,则x²-3xy+2y²/2x²-9xy+7y²的值为