Question

求分式值已知3x-4y=0,求x∧2-3xy／3x∧2﹢y∧2的值

Answer 1

因3x-4y=0,所以x=4y/3,在分式两边同时乘以x,则x2=4yx/3,xy=3x2/4,在分式两边同时乘以y,则y2=3yx/4,将x2=4yx/3,xy=3x2/4,y2=3yx/4,代入x∧2-3xy／3x∧2﹢y∧2中可求出其为：-20/57.