Question

f(x,y)=3xy/(x^2-y^2);求f(y/x,1)

Answer 1

f(x,y)=3xy/(x^2-y^2);

即f(a,b)=3ab/(a^2-b^2);

求f(y/x,1)即将上式中的a ,b 分别用y/x,1代入上式

f(y/x,1)=(3*y/x*1)/(y^2/x^2-1)

=3xy/(y^2-x^2)