Answer :

3x+x=y
3(-3)+(-3)=y
-9-3=y
-12=y

Therefore the value of x3+x is -12

[tex] x^{3} + x [/tex]

x= -3

Plug the value of x into the equation. x = -3

After putting the value of x in it now looks like:

[tex] -3^{3} + (-3) [/tex]

Now solve:
[tex] -3^{3} [/tex] is the same as:  (-3) x (-3) x (-3)    

(-3) x (-3) x (-3) = -27 

Finish the equation by adding -3 to -27 (same thing as subtracting 3 from -27)
-27 + (-3) = -30


x = -30