Question

Which of the following is not a factor of x^3 – 3x^2 – 4x + 12?

Answer 1

Answer:

c. (x + 3)

Step-by-step explanation:

using factor theorem

if x - 3 is a factor then p(a) = 0

p(a)= x^3 - 3x^2 - 4x + 12

a.(x-3)

p(3) = (3)^3 - 3(3)^2 - 4(3) + 12

= 27 - 27 - 12 + 12

= 0

therefore x-3 is a factor

b.(x + 2)

p(-2) = (-2)^3 - 3(-2)^2 - 4(-2) + 12

= -8 -12 + 8 + 12

,= 0

therefore x + 2 is a factor

c.(x + 3)

p(-3) = (-3)^3 - 3(-3)^2 - 4(-3) + 12

= -27 -27 + 12 + 12

= -30

therefore x + 3 is not a factor

d.(x-2)

p(2) = (2)^3 - 3(2)^2 - 4(2) + 12

= 8 -12 - 8 + 12

= 0

therefore x - 2 is a factor