`U = (x^2 - y^2)/(x^2 + y^2) and v = (2xy)/(x^2 + y^2)` then what is relation between `u and v`​

u=(x^(2)-y^(2))/(x^(2)+y^(2)) find d(u)/(dx)?

If (4x^2-3y^2):(2x^2+5y^2)=12:19 then x:y=

If x^(4) + x^(2) y^(2) + y^(4) = 91 and x^(2) - xy + y^(2) = 13 , then what is the value of | x-y|?

The coefficient of correlation between X and Y is 0.6 U and V are two variables defined as U=(x-3)/(2), V=(y-2)/(3) , then the coefficient of correlation between U and V is

If x^(4)+x^(2)y^(2)+y^(4)=133 and x^(2)-xy+y^(2)=7, then what is the value of xy ?

If x^(4) +x^(2)y^(2)+y^(4)=21 , and x^(2)+xy+y^(2)=3 then what is the value of 4xy?

u=(x-20)/(5) and v=(y-30)/4, then b_(xy) =

(x-y)^(2) (dy)/(dx) =a^(2), x -y =u