What are two equivalent ratios for 1/9

Acertain population of bacteria demonstrates exponential growth doubles in size every 4 days. how long will it take the population to triple in size?

What are the solutions of the equation? 5z^2 + 9z - 2 = 0 a. 1, -2 b. 1, 2 c. 1/5, -2 d. 1/5, 2

Aclassmate thinks that solving a system by graphing gives an exact answer when the lines appear to cross at a grid point, but only an approximate answer when they don't. explain why this isn't true.