Rivkah Carl, I work at Noodle
Great question! A parent function is the most simple function of a group of functions in which the group of functions keeps the same "shape". Some examples of groups of functions are : linear (graph looks like a line) or quadratic (graph looks curved) etc. The parent functions of those groups which means the most simple linear function or the most simple quadratic function are y=x or y=x^2. This means that even if you have a function of y=x+5, or y=5x the same shape is kept but the graph is shifted (either up or down or in steepness of a line). Look at your function and try to determine the "group" of functions to which it belongs. Then you can see what would be the parent function for that group. Good luck!