jmc

The fourth degree polynomial equation $x^4-7x^3+4x^2+7x-4=0$ has four real roots, $a$, $b$, $c$ and $d$. What is the value of the sum $\frac{1}{a}+\frac{1}{b}+\frac{1}{c}+\frac{1}{d}$? Express your answer as a common fraction.