若x/y=2/7则7x²-3xy+2y²/2x²-3xy+7y²=x 2 7x²-3xy+2y²__= __ _____________ =y 7 2x²-3xy+7y²

问题描述:

若x/y=2/7则7x²-3xy+2y²/2x²-3xy+7y²=
x 2 7x²-3xy+2y²
__= __ _____________ =
y 7 2x²-3xy+7y²