(3x^2-2xy+5y^2)/(5x^2-3xy+3y^2) 分子分母同时除以y²
=[3(x/y)²-2(x/y)+5]/[5(x/y)²-3(x/y)+3]
=(4/3-4/3+5)/(20/9-2+3)
=5/(29/9)
=45/29