Hello friends! It’s Ella... how is everyone?

Compare the cost of the bike trips from the two companies shown.for both the cost in a linear function of the number of days which statements is true

[10 points, algebra 2]according to my answer key the restrictions are -1 and 4. but why not positive 1?

For problems 29 - 31 the graph of a quadratic function y=ax^2 + bx + c is shown. tell whether the discriminant of ax^2 + bx + c = 0 is positive, negative, or zero.