Express f(x)= (3a-5x)/((3a+2x)(2a-x)) in partial fractions. I don't know how to solve a partial fraction with 2 unknown variables.
Find the complex numbers z for which (z+4)/(z + 4i) is real and the argument is equal to root of 10. Give the answer in the form z = x + iy), where x and y are real. I don't know what is meant by a multiple of z´s and how to find them, and I don't understand why z is inside the equation when I understand it as representing the equation z = x+iy.)
The equation of a curve is xy + (y^2) (e^-x)=4. Show that dy/dx = (y^2 - ye^x) / (xe^x +2y). I don't know how to isolate the y to find the derivative.)