Which expressions are polynomials? select each answer. a) -x^2+5x b)-7x^2+5/3x c) x^2+5x^1/5 d)6x^2+5x

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,

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).