Why does the specific quadrant that an angle is found in matter when solving trigonometric functions

Just tell me how to set up the equation.

David estimated he had about 20 fish in his pond. a year later, there were about 1.5 times as many fish. the year after that, the number of fish increased by a factor of 1.5 again. the number of fish is modeled by f(x)=20(1.5)^x. create a question you could ask that could be answered only by graphing or using a logarithm.

What is r i 4.5+10r=-6.5 with work pls