We can check our answer by substituting the given zeros for x. If the result is y=0, it means that the given numbers are actually zeros of the function and our answer is correct. Let's start by checking 1.
y=x^3-6x^2+11x-6
y= 1^3-6( 1)^2+11( 1)-6
y=1-6(1)+11(1)-6
y=1-6+11-6
y=0 ✓
We proved that 1 is a zero of the function. Let's now check 2.
y=x^3-6x^2+11x-6
y= 2^3-6( 2)^2+11( 2)-6
y=8-6(4)+11(2)-6
y=8-24+22-6
y=0 ✓
We have shown that 2 is also a zero. Finally, let's see what happens with 3.
y=x^3-6x^2+11x-6
y= 3^3-6( 3)^2+11( 3)-6
y=27-6(9)+11(3)-6
y=27-54+33-6
y=0 ✓
We found that 3 is also a zero. Since 1, 2, and 3 are zeros of the polynomial function, our answer is correct.