Draw the gragh of the given polynomials and find the zero and justify

This question was asked in Example 3

Draw the gragh of the given polynomials and find the zero and justify your answer
1.p(x)=x^2-x-12
2.p(x)=x^2-6x 9
3.p(x)=x^2-4x 5
4.p(x)=x^2 3x-4
5.p(x)=x^2-1