Hello! I am having trouble with these Calculus problems (Volume of a solid rotation). If anyone could help that would be great. Ignore the answers that are already selected, I just cannot unselect them.

The equation x2 – 1x – 90 = 0 has solutions {a, b}. what is a + b?

X/y + 4y/x divided by x/y - 2y/x explain as in depth as you can how you simplfied the fractions. i don't know where to start on this : /

Afunction, f(x), represents the height of a plant x months after being planted. students measure and record the height on a monthly basis. select the appropriate domain for this situation. a. the set of all positive real numbers b. the set of all integers oc. the set of all positive integers od. the set of all real numbers reset next