Answer 1

Let the numbw-er k be added and resulting polnomic be f(x). 

So, f(x) =`3x^3+5x^2+6x+k`  

it is given that when f(x)is dividing by (x-3), the remainder is 8. 

∴ f(3)=8 

`3(3)^3-5(3)^2+6(3)+k=8` 

`81-45+18+k=8` 

`54+k=8`

`k=-46` 

Thus, the required number is  -46.