Need help don’t know what to do I’m confused

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

A33 gram sample of a substance that's used to detect explosives has a k-value of 0.1473. n = noekt no = initial mass (at time t = 0) n = mass at time t k = a positive constant that depends on the substance itself and on the units used to measure time t = time, in days

Look at the hyperbola graphed below. the hyperbola gets very close to the red lines on the graph, but it never touches them. which term describes each of the red lines? o o o o a. asymptote b. directrix c. focus d. axis