Answer: The answer are (a) -x² + 5x and (d) 6x² + 5x.
Step-by-step explanation: We are given four different expressions out of which we are to select those which are polynomials.
We know that a polynomial is a combination of an unknown variable and its non-negative powers with real coefficients. For example,
[tex]ax^3+bx^2+cx+d[/tex] is a third degree polynomial with constant coefficients a, b, c and d.
Since a polynomial does not involve negative poers of the unknown variable, so the options (b) and (c) are not correct.
Thus, the correct options are (a) and (d).
