已知x/y=3,求2x²-3xy+5y²/x²+3xy-y²的值
问题描述:
已知x/y=3,求2x²-3xy+5y²/x²+3xy-y²的值
答
x/y=3,则x=3y,于是(2x²-3xy+5y²)/(x²+3xy-y²)=(2*9y²-3y*3y+5y²)/(9y²+3y*3y-y²)=(18y²-9y²+5y²)/(9y²+9y²-y²)=(14y²)/(17y²...