What happens to f(x) when x is negative but approaches zero for the function f(x)=1/x

Iwant to know what 3g+5h+4g-2h is my teacher is too selfish to tell us

Given that ot =5, xt=12, and ox= 13 is xy tangent to circle o at t? explain.

You are standing next to a really big circular lake. you want to measure the diameter of the lake, but you don't want to have to swim across with a measuring tape! you decide to walk around the perimeter of the lake and measure its circumference, and find that it's 400\pi\text{ m}400? m. what is the diameter dd of the lake?