If α,β and γ are the zeros of a cubic polynomial P(x)=ax3+bx2+cx+d,a≠0 then,
Product of the zeros of P(x)=αβγ=−da
Here, a=1, b=4, c=1, and d=−6
⇒ product of zero of cubic polynomial P(x)
⇒αβγ=−da
⇒αβγ=−(−6)1=6