Question

Zeros of cubic polynomial ax³ +3x² -bx - 6 are - 1 and - 2. Find the third zero and value of a and b

Answer 1

$\gamma + \beta + \alpha = - b \div a$

-1-2+ gamma= -3/a

-1*-2*gamma= 6/a

2 gamma= 6/a

gamma= 3/a

-3+3/a= -3/a

-3= -6/a

1= 2/a

a=2

gamma= 3/2

Other zero = 3/2

$b = \gamma \beta + \gamma \alpha + \beta \alpha$

b= -1-2+ -1+3/2 + -2+3/2

= -3