Question

if x =3y-3 then find x³-27y³+27xy+27​

Answer 1

) x=3y-3 --------------------------(1)

cubing both sides,

x³=27y³-27-3.3y.3(3y-3) [(x-y)³=x³-y³-3xy(x-y)]

or, x³=27y³-27-27y(x) ; [using (1)]

or, x³-27y³+27=-27xy