algebra
posted by rinku .
factorise the left hand side of the equation xxx+7xx21x27=0 and the roots are

simplified to
x^3 + 7x^2  21x  27 = 0
try: x = ±1, ±3, ±7
on the second try, I got x=1 to work
so (x+1) is a factor
by synthetic division I found
x^3 + 7x^2  21x  27 = (x+1)(x^2 + 6x  27) = 0
(x+1)(x+9)(x3) = 0
x = 1, 9, and 3