4.2.1) \( 7 x-2 x^{2}-x+x^{2} \)

To simplify the expression, first combine like terms. You have \( 7x \) and \( -x \) which together give \( 6x \). Next, combine \( -2x^2 \) and \( x^2 \) which results in \( -x^2 \). So, the simplified expression is \( -x^2 + 6x \) or, rearranged, \( -x^2 + 6x \). Now, if you were to factor this expression, you could pull out a common factor of \( -1 \), giving you \( -1(x^2 - 6x) \). From there, you can factor further to obtain \( -1(x(x - 6)) \). This way, you’ve not only simplified but also factored the expression!