The fourth degree polynomial equation x4−7x3+4x2+7x−4=0 has four real roots, a, b, c, and d. What is the value of the sum 1a+1b+1c+1d? Express your answer as a common fraction.
abcd=c0=−4bcd+acd+abd+abc=−(c1)=−71a+1b+1c+1d=bcd+acd+abd+abcabcd=−7−4=74