from given eqn,

++ = -b/a ; ++ = c/a ;  = -d/a

roots of req. eqn r (  - 1)/ ; (  - 1)/ ; ( - 1)/

consider l,m,n such dat they r reciprocals of abv 3

l+m+n = ( +  + ) /( - 1) = -c/(a+d)

lm+ln+mn = (++) *  / (  - 1) = -bd/(a+d)²

lmn = ()² / ( - 1)³ = -ad² / (a+d)³

eqn whose roots r l,m,n  is (a+d)³x³ + (a+d)²cx² - bd(a+d)x + ad² = 0

to obtain req, eqn change x 2 1/x

ad²x³ - bd(a+d)x² + (a+d)²cx + (a+d)³ = 0