Please help me with this problem so I can help my son better understand I have attached an image of what were working on. Multiply.(3x+1)(x−1) Express the answer in standard form.Enter your answer in the box.

Explanation:
We are told to express the given question in standard form,
To do this, we will use the FOIL method
This is method is shown below
In solving the question
[tex](3x+1)(x-1)[/tex]Applying this, we will have
[tex]\begin{gathered} First=3x\times x=3x^2 \\ Outer=3x\times-1=-3x \\ \text{Inner}=1\times x=x \\ \text{Last}=1\times-1=-1 \end{gathered}[/tex]Therefore the standard form will be to combine the terms above and then simplify
[tex]\begin{gathered} =3x^2-3x+x-1 \\ =3x^2-2x-1 \end{gathered}[/tex]Therefore, the answer in standard form is
3x²-2x-1