Find the volume of the sphere round the answer to the nearest 10th

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

Find the roots of the polynomial function f(x) = x^3 + 2x^2 + x

When you have 25 numbers, and jake picks 3 random numbers and puts them back, what is the chance bob has of picking those 3 numbers when he picks 6 random numbers (without putting them back)? explain.