Question

check whether 7+3x is a factor of 3x(cube)+7x

Answer 1

7+3x=0
3x=0-7
3x=-7
x=-7/3

p(-7/3)=3*(-7/3)(cube)+7*-7/3
=3*-343/27-49/3
=-343/9-49/3
-490/9

Answer 2

3x^3 +7x = x(3x^2 +7)
- so not is a factor

Answer 3

oh its not a factor