Question

If one of zeroes of the cubic polynomial $x^3+a{x}^2+bx+c$ is -1 , then the product of the other two zeroes is

• A. $a-b+1$
• B. $a-b-1$
• C. $b-a+1$
• D. $b-a-1$

Answer 1

The correct option is C $b-a+1$

If $a{x}^3+b{x}^2+cx+d$ be a cubic polynomial , zeroes of it are $p,q,r$ then,

$p+q+r=\frac{-b}{a},pq+qr+pr=\frac{c}{a},pqr=\frac{-d}{a}$

given $-1$ is a zero let the other 2 zeroes be $p,q$.

$p+q-1=-a,pq=c,pq-p-q=b$

$p+q=1-a,pq=b+p+q=c$

$pq=b+1-a$