Let's analyze and simplify the expressions from the image:

Expression 3:
$3x^3 - x^2 + x$

This expression is already in its simplest form and can't be factored further using standard factoring techniques. It's a cubic polynomial with terms $3x^3$, $-x^2$, and $+x$.

Expression 4:
$2ax^2 + 2axy - 3bxy - 3bx^2$

Here we can simplify by grouping like terms:

1. Group the terms with $x^2$ and $xy$ together: $(2ax^2 - 3bx^2) + (2axy - 3bxy)$

2. Factor out common terms: $x^2(2a - 3b) + xy(2a - 3b)$

3. Notice that both terms have a common factor of $(2a - 3b)$, so we can factor it out: $(2a - 3b)(x^2 + xy)$

Thus, the factored form of expression 4 is: $(2a - 3b)(x^2 + xy)$

Would you like further details on these steps or have any questions?

Here are 5 questions for further exploration:

1. How can we determine whether a cubic polynomial can be factored?
2. What are the conditions for grouping terms in polynomials?
3. Can this approach be used for higher-degree polynomials as well?
4. What is the significance of factoring in solving algebraic equations?
5. How does factoring help in graphing polynomial functions?

Tip: When factoring, always look for common terms or patterns such as difference of squares or perfect square trinomials to simplify expressions efficiently.