Find all the zero

Consider 3x³ + 10x² – 9x – 4,

Since 1 is the zero of the given polynomial.

So, (x-1) is the factor of the polynomial.

So, 3x³ + 10x² – 9x – 4 = (x-1)(3x² + 13x +4)

Now, 3x² + 13x +4 = 3x² + 12x + x +4

= 3x (x + 4) + 1 (x+4)

= (3x+1) (x+4)

So, zeroes will be

Thus, the zeroes will be x = -4, , and 1.