Question

what are the excluded values of -7z/4z+1

Answer 1

Values of z that make the denominator zero are excluded.

As written, there are no excluded values.
.. ((-7z/4) * z) +1

If you intend
.. (-7z)/(4z) +1 . . . . . then z=0 is excluded

If you intend
.. (-7z)/(4z +1) . . . . then z = -1/4 is excluded