Verified answer

Answer:

k= -40

Step-by-step explanation:

Given,

p(x)= -x³ + x + 3k

(x+5) is a factor of p(x)

therefore, -5 is a zero of p(x)

That implies,

p(-5)=0

=> -(-5)³ + (-5) + 3k =0

=> 125-5 +3k =0

=> 3k = -120

=> k = -40