Question

Given f(x)=3x^3-4x+k and x+2 is a factor of f(x), then what is the value of k?

Answer 1

Answer:

k is 16

Step-by-step explanation:

Factor is ( x+2 ):

${ \sf{x + 2 = 0}} \\ { \sf{x = - 2}}$

Root is -2.

${ \bf{f(x) = 3 {x}^{3} - 4x + k}} \\ { \sf{f( - 2) = 0}} \\ { \sf{3 {( - 2)}^{3} - 4( - 2) + k = 0 }} \\ { \sf{ - 24 + 8 + k = 0}} \\ { \sf{ - 16 + k = 0}} \\ { \sf{k = 16}}$

Answer 2

Hope this helps you !!