$w\left(-1\right)={\left(-1\right)}^4+5\cdot {\left(-1\right)}^3+5\cdot {\left(-1\right)}^2-5\cdot \left(-1\right)-6=$  

$=1-5+5+5-6=0$     

$w\left(2\right)=2^4+5\cdot 2^3+5\cdot 2^2-5\cdot 2-6=$  

$=16+5\cdot 8+5\cdot 4-10-6=$  

$=16+40+20-16=60$  

$w\left(-2\right)={\left(-2\right)}^4+5\cdot {\left(-2\right)}^3+5\cdot {\left(-2\right)}^2-5\cdot \left(-2\right)-6=$  

$=16+5\cdot \left(-8\right)+5\cdot 4+10-6=$  

$=16-40+20+10-6=0$  

$w\left(3\right)=3^4+5\cdot 3^3+5\cdot 3^2-5\cdot 3-6=$  

$=81+5\cdot 27+5\cdot 9-15-6=$  

$=81+135+45-21=240$  

$w\left(-3\right)={\left(-3\right)}^4+5\cdot {\left(-3\right)}^3+5\cdot {\left(-3\right)}^2-5\cdot \left(-3\right)-6=$  

$=81+5\cdot \left(-27\right)+5\cdot 9+15-6=$  

$=81-135+45+15-6=0$